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 Book_ 
 
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 COPyRIGIIT DEPOSm 
 
SUCCESSFUL 
 INCUBATION 
 
 A WORKING MANUAL FOR 
 LARGE HATCHING PLANTS 
 
 BY P. COOK 
 
 Proprietor OF the MAMMOTH BA.TCHERY 
 LOS ANGELES CvWL. 
 
 / Xf 
 
 PRICE, ^l.OO NET 
 
 PUBLISHED BY THE 
 
 WEIMAR PRESS 
 
 301i5 S. MAIN ST.. LOS ANGELES.CAL. 
 
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 Copyright, 1 9 
 By P. Cook. 
 
 Cci.a;<jso7.s<: 
 

 PREFACE 
 
 A. 
 
 « This little book gives oar experiences in hatching 
 conducted for about six years. It is the story of our 
 investigations, how we have finally stumbled on to the 
 right way to hatch chicks. It is hoped it will save many 
 the heart-rending experiences we have gone through. 
 When you once know how, it is simple enough to hatch 
 chicks, but it is not always easy to find out the simple 
 way. 
 
 We also hope that there will be no disappointment 
 to our readers. It seems that most poultry books are 
 written by persons sitting by a cosy fire spinning theo- 
 ries that are utterly impracticable. This book is based 
 on actual hatchery work and every effort has been made 
 not to mislead any one or make claims unsupported by 
 actual facts. 
 
 But there is still room for improvement and we shall 
 be glad to hear from our readers if difficulties persist. 
 All letters to me should be addressed to the publishers 
 of the book, and they will be forwarded. 
 
 The price of the book may seem high to many per- 
 sons, but it costs a great deal to publish a book. It is 
 not the paper it is printed on, but the advertising that 
 costs, and it is more than doubtful whether the pub- 
 lishers will ever be adequately paid for it even at its 
 high price. It contains real information, that will be 
 worth tenfold its price to any reader even the first year 
 he uses an incubator. 
 
 Moreover, it must be remembered that all the inven- 
 tions of this book are given free to the public, there are 
 no patents on any of them. Everybody is at liberty to 
 use what he likes. The proceeds from the book is the 
 only remuneration the author receives. 
 
 P. COOK. 
 
 Los Angeles. Cal., Jan. 1, 1911. 
 
DESCRIPTION OF P. COOK'S INCUBATOR 
 
 (See Diagram on Preceding Page) 
 
 Fig. 1. a, jacket enclosing boiler. This communi- 
 cates with the outer air around its lower rim. The air 
 thus heated by the sides of the boiler passes into the 
 upper compartment of the incubator through the open- 
 ing e, during incubation there is no other ventilation. It 
 will be seen at once that this method procures a great 
 deal of superheated air, which helps to take care of the 
 evaporation from the eggs without unduly increasing the 
 humidity of the egg-chamber, b, small tubes through 
 which heat from the lamp, y, passes through the boiler, c, 
 when the damper of the regulator is down. When 
 damper is raised, the heat passes directly from the lamp 
 through the large centre tube, o, without heating it, n, 
 is a collar or rim compelling the heat from the lamp 
 to ascend through small tubes, instead of dissipating be- 
 low the boiler; f, portion of return pipe from incubator; 
 d, portion of outflow pipe or coil entering incubator; h, 
 thin muslin diaphragm separating upper and lower com- 
 partment of incubator, preventing any draft from air en- 
 tering at e; k, egg tray; i, nursery; m, incubator legs; 
 p, ventilating tube, used to dry off chicks after hatch- 
 ing. Kept closed during incubation. 
 
 Fig. II. r, incubator; s, drawer containing nursery 
 and egg tray; t, stick on which drawer rests when pulled 
 out. 
 
 Note. — All the experiments and successful hatches de- 
 scribed in this book have been made with machines con- 
 forming strictly to this type. We have so far found this 
 the most successful type, and used it equally well with 
 hot air as with hot water heating. 
 
INCUBATOR INSTRUMENTS 
 
 P. Cook's Carbonic Acid Gas Test, complete set of all neces- 
 sary' instruments, $5.00 
 
 P. Cook's Hygrometer, continuous reading, $3.00 
 
 P. Cook's Simplified Hygrometer $ 1 .00 postpaid 
 
 ( No one using an incubator should be without at least the 
 Simplified Hygrometer. The other instruments are for 
 large hatcheries.) 
 
 For sale by P. COOK, 301 7 S. Main St., Los Angeles. Cal. 
 
 Note to page 2 1 —.No carbonic acid gas is given off by the 
 body of the hen. We have made many tests to that 
 effect. All that is found under her comes from the 
 respiration of the embi^yo. 
 
SUCCESSFUL INCUBATION 
 
 SOME EXPERIENCES WITH INCUBATORS. 
 
 Some of the strangest experiences take place with in- 
 cubators. We have had our share of them. The 
 very first incubator we bought happened to be a good 
 one, and we had reasonably good hatches out of it, yet 
 a considerable proportion of the chicks died in the shells. 
 We supposed that with more experience we would be 
 able to get better hatches, but the contrary proved to 
 be the case. After two hatches we moved this incubator 
 to another building, and we had nothing but poor hatches 
 from it in spite of the best of our care, so we gave up 
 that kind of an incubator. Then we heard of one 
 that was producing very good hatches through an ac- 
 quaintance, and we invested in that make, but it would 
 not hatch for us in any way at all. We tried it six or 
 seven times, and lost practically every hatch. Then it 
 was moved to another room, and as we were badly need- 
 ing an incubator to take care of some surplus eggs, we 
 decided to run it once more, and the machine has given 
 very good hatches to the present date, standing in this 
 one place. 
 
 In the meantime we also built different types of in- 
 cubators of our own to find out, if possible, the difficulties 
 in incubation, and though we constructed over thirty 
 different types of machines, and tried almost every con- 
 ceivable method we did not seem to make any particu- 
 lar headway. It was always the same old story, some- 
 times a very good hatch, and then a number of very bad 
 ones. We tried it three times with one very popular 
 make of incubator, and in each hatch as many chicks 
 were dead in their shells as those that succeeded in get- 
 ting out. We sold the machine in disgust. The man 
 who bought it from us moved it to his house, and the 
 machine hatched every fertile egg, although he had never 
 run an incubator before. 
 
 We had another machine which we built ourselves 
 that gave a very remarkable hatch, and we hoped we 
 were nearing the goal. We moved it to another room 
 in our hatchery, and it would not hatch there at all. 
 And more perplexing still was another case of a ma- 
 chine holding about 1000 eggs. It had four drawers, 
 and the two drawers in the rear end of the machine 
 always batched very well. The two drawers in the other 
 end of the machine, while the temperature was the same 
 throughout, never hatched at all, i. e., most of the chicks 
 died in the shell, or were cripples, though it was im- 
 possible to discover any difference in the machine. 
 
 Another peculiar case we had was this: Someone 
 brought us some eggs on which a hen had set for four 
 
days, and then died on the nest. It was about IS hours 
 after the hen was dead that the eggs were brought to us, 
 and the eggs were stone cold when they arrived. We 
 placed them in an incubator with 3 00 eggs in it, which 
 had been set just about the same time. At the time of 
 hatching we secured nine strong, lively chicks from the 
 eggs the hen had set on, and there was only one egg 
 which was fertile that failed to hatch of the hen's 
 clutch, but the 300 in the incubator practically did not 
 hatch at all, i. e., there were about fifty miserable chicks 
 that got out. The rest did not get out of the shell at all. 
 
 We have tried a great variety of different makes of 
 machines, and we have had the same story with all of 
 them. Sometimes they hatch very well, and sometimes 
 they do not hatch at all. Most of the time there are 
 more dead chicks in the shell than there ought to be 
 with all of them. Some machines are far better built 
 than others, but even the poorest made machines have 
 given us just as good hatches, as the most expensive 
 ones. 
 
 The glowing testimonials which all the incubator man- 
 ufacturers send out are i)robably genuine, as we could 
 duplicate most of them once in a while. Nearly every 
 make of machine we have seen sometimes give as good 
 hatches as claimed, but there is always against the 
 one success a woeful lot of failures. Of course, if eggs 
 are exceptionally strong and vigorous in fertility, they 
 will perhaps hatch under almost any conditions, but 
 the great necessity for poultry raising is to get an in- 
 cubator that will hatch nearly as well as the hen, and 
 in all our experiences w'ith the hens we have found 
 that, barring accident, she succeeds in hatching practi- 
 cally all the fertile eggs. We soon became convinced, 
 of course, that something must be wrong with the in- 
 cubator, but the harder we tried to find out the farther 
 we seemed to be from the goal. 
 
 It is easy to build a new incubator, and build one 
 that one thinks is a great imi)rovement. Ninety-nine 
 times out of one hundred it will be found, however, 
 that the new machine is worse than the old one. It is 
 needless to rehearse the whole history of our experiences. 
 I simply mention these things to show that in the way 
 incubators have been constructed hitherto some vital 
 things have been lacking, and if anyone has experiences 
 similar to these, he must remember that every other 
 poultry man is apt to find such happenings some time 
 or other. It is true, some poultrymen have been Singu- 
 larly fortunate in having almost always good hatches, 
 and others have been singularly unfortunate, in al- 
 most always having very poor hatches. However, we 
 think that, in the following pages we describe a method 
 which will enable anyone to secure hatches nearly as 
 good as those the hen produces. 
 
 So far as we know we have good reason to believe that 
 the essential principles of incubation have been discov- 
 ered, and the only thing that remains to be done is to 
 
 8 
 
reach a greater perfection of our method. At any rate, 
 the only way to discover the right method is by un- 
 ceasing experiments, and we shall be very glad if persons 
 who follow our method will report to us the success, or 
 lack of success, which they have. We hope for the heart- 
 iest co-operation in this respect, as the first principle 
 in successful poultry keeping, is the successful hatching 
 of strong, vigorous chicks. 
 
 It is certain that in an incubator where fifty per cent 
 of the chicks die in the shell, the chicks that actually do 
 get out have not been incubated under desirable condi- 
 tions, and must have suffered considerable, which means 
 that they are handicapped from the first. 
 
 It is an unfortunate thing that it is almost next to 
 impossible to have people willing to acknowledge their 
 failures in hatching. Every body seems to think it a 
 disgrace to acknowledge the unsuccessful hatching of his 
 eggs. It is time that there be a little more honesty 
 among poultry men in this respect, and if anyone has 
 discovered a successful way of hatching he should be 
 willing to let his neighbors know it. 
 
 We believe that we have made very important discov- 
 eries and therefore publish this little volume, but we de- 
 sire to have it taken as an incentive to more careful ex- 
 periments, much rather than as an entire solution of the 
 problem. 
 
 The most careful methods are necessary for this in- 
 vestigation, and much patience must be exercised, but 
 the fact that every once in a while an incubator pro- 
 duces perfect hatches shows beyond a doubt that the 
 goal of unfailing success is attainable, and if we are 
 patient enough and work hard enough we shall finally 
 wrest from nature her secrets. 
 
 HOT WATER OR HOT AIR INCUBATORS. 
 
 We have used very extensively in our tests, both hot 
 water and hot air incubators, and so far as the hatching 
 of eggs is concerned, it makes not the slightest difference 
 which is used, providing it is constructed properly. 
 
 Manufacturers of hot water machines should see to it 
 that their hot water tanks are well made, and especially 
 should avoid any combination of galvanized iron with 
 brass or copper, as these are sure to leak in a very short 
 time, on account of electrolysis. 
 
 We should advise, however, for all small machines, the 
 use of hot air, as we have found in our experience that 
 it gives much less trouble. If once such incubators are 
 built right, they last practically a life time. The heat 
 is not as even in a hot air machine, as it can be made in 
 a hot water machine. But a little unevenness of heat 
 seems to be of no importance. The hot-air machine is 
 less trouble to take care of than the hot water machine. 
 However, the hot air machines can hardly be built suc- 
 cessfully to take care of more than 5 eggs. If larger 
 machines are to be used, hot water is required. 
 
We have also experimented witli a yreat many differ- 
 ent boiler systems, but find a copper boiler with a large 
 tube through the center, and a series of small tubes run- 
 ning parallel with it between the large center tube and 
 the sides of the boiler, to be the most successful. The 
 damper is placed over the large center tube connected 
 with a thermostat. When the damper rises, the heat 
 from the lamp or gas flame passes directly through the 
 center tube without heating any water in the boiler. 
 When the damper is closed the heat passes up the center 
 tube and returns through the smaller tubes before find- 
 ing an outlet, thus giving an immense heat surface. 
 
 The requirements for incubator boilers are that they 
 should have an immense heating surface when the dam- 
 per is closed, and when the damper is open none, or at 
 least only a very small amount of heat should pass to 
 the boiler. 
 
 The best circulating system we have found to be 
 wrought iron pipe connected in the ordinary way to 
 the boiler, but the outflow pipes should be connected 
 to the top of the boiler, and the return flow should enter 
 the bottom of the boiler. The boiler always must be 
 placed somewhat lower than the outflow pipes. In our 
 practice we place the outflow pipes at the top of the 
 boiler, and let them rise gradually about one inch, or 
 sometimes two inches to the extreme back of the ma- 
 chine, and then let the return pipe have a fall of about 
 two inches through the length of the incubator, and then 
 let it pass down to the bottom of he boiler. It does 
 not make any difference how far the highest point of the 
 pipe is from the boiler, as hot water will rise to the top, 
 but there must be an even fall from the highest point 
 to the return, in order to insure good circulation. 
 
 In hot air machines the difficulty is to spread out the 
 heat toward the sides. There are several ways which 
 seem to do the work equally well, and a number of differ- 
 ent systems are in use on the incubators on the market. 
 We cannot see that one has any advantage over the other. 
 
 HINTS TO THE MANUFACTURERS OF INCUBATORS. 
 
 Incubator Case, Doors, Etc. 
 
 There are very few incubators on the market at the 
 present day that are built sufficiently well for the pur- 
 pose for which they are intended. Many incubators are 
 built so cheaply, and in so slovenly a manner that no 
 man who cares to hatch eggs should ever be tempted to 
 buy them, no matter at what price they are offered. They 
 are too expensive even if they were given away. The 
 first requirement for success in raising poultry is to hatch 
 strong and vigorous chicks, and unless an incubator is 
 well built, you cannot possibly do this. It is not the ma- 
 terial that is used in the incubator which is of so much 
 consequence, but the workmanship in putting it together 
 is of the very greatest importance. Every incubator 
 
 10 
 
should be built of double walls throughout, and at least 
 on top, should have a thoroughly heavy packing of heat 
 insulating material. But more important than the pack- 
 ing is the care with which joints are made. They should 
 be made on proper machinery and carefully glued 
 together, so as to make the. incubator case air-tight, es- 
 pecially the door should be made to fit absolutely air 
 tight. This is almost impossible to accomplish unless the 
 edges of the door and its casings are lined with felt. 
 There should be double doors, one glass door next to 
 the eggs, and outside of that a solid wood door. This 
 is preferable, for if chicks are kept in the dark while 
 hatching they will remain evenly scattered over the in- 
 cubator. If there is only one glass door chicks will all 
 crowd to the front. This may be obviated somewhat by 
 placing the glass high up in the door, and leaving a con- 
 siderable dark space at the bottom, which keeps the light 
 out of the nursery. But far better than the arrange- 
 ment of glass doors, and egg trays is the method of con- 
 struction used in our Mammoth machines. These have 
 simply a large drawer, which fits tightly in the machine. 
 The egg trays are placed within this drawer, near its 
 top, and for airing the eggs, the whole drawer is pulled 
 out of the machine resting one end upon the incubator, 
 and the other on a stick fastened to the front of the 
 drawer. A small window screened with curtains is cut 
 in the upper part of the drawer through which the tem- 
 perature may be read, and chicks may be watched at the 
 time of hatching. This arrangement saves a very large 
 amount of labor, as the chicks can easily be gotten out, 
 and the eggs are always protected from drafts, as the 
 sides and bottom of the drawer are solid, and thus pre- 
 vent any drafts from striking the eggs. 
 
 THERMOSTAT, LAMPS, ETC. 
 
 It is immaterial v/hat kind of thermostat is used, 
 whether it be composed of different metals, or ether 
 wafers. Everything here, as everywhere else, depends 
 upon the care with which they are made. Either kind 
 will last a life time, if well made, but it is quite important 
 that all the bearings should have knife edges and should 
 be patterned after the method of bearings used in weigh- 
 ing-scales. 
 
 When possible only one direct lever should be used, 
 and the method of regulating the heat should be that 
 which is commonly known as the damper method. Any 
 thermostat working on the v/ick of the lamp is always 
 more or less unreliable, as the wick sleeves are sure to 
 char some time or other, and thus prevent its working. 
 While there is a little saving of oil on the lamp trips, 
 they are sure to spoil the hatch sooner or later, and thus 
 may be expensive in the end. 
 
 Lamp bowls should be made either of galvanized iron 
 or copper or brass, and they should be well and strongly 
 
 II 
 
made, and the upper part of the lamp bowl should be po:- 
 fectly smooth, sloping toward the edges, so that no oil 
 will stand on it. 
 
 If the boiler of the incubator is constructed properly, 
 arrangements to keep water on the lamp, or around the 
 flame are unnecessary, and had better not be used. The 
 final outlet of the bad air from the lani]) should be at 
 least twelve vertical inches above the flame, no matter how 
 far endways, or sideways this outlet is found. Other- 
 wise there will be heating of the lamp flame, and of the 
 lamp bow], and there is danger of generating explosive 
 gases. 
 
 Lamj) chimneys should be made of iron with a large 
 mica window at least 2 inches in diameter, but see that 
 your chimneys are faultlessly made, for drafts from the 
 chimneys will cause the lamp-flame to smoke, and be- 
 come dangerous. The lamp on any incubator should be 
 carefully locked. No si)ring arrangement is ever to be 
 allowed, for springs, no matter how good they are, will 
 get weak in a short time, and the lamp will not fit prop- 
 erly. The lamp should be so securely locked to the in- 
 cubator that it cannot be knocked off; even if the incu- 
 bator should be overturned the lami) should still stick 
 to it. To encase the incubator in metal is useless, the 
 danger comes from the lamp, not from the incubator. 
 Common sense requires these precautions. 
 
 Thermostats should have a protective covering so that 
 cats and dogs, or children or plaster that may fall from 
 the wall on them, would not throw them out of position. 
 It is to be remembered that any thermostat must of ne- 
 cessity be a delicate instrument, and it should be made 
 accordingly, and treated accordingly. 
 
 CARE OF BREEDING STOCK AXJ) FERTILITY 
 OF EGGS. 
 
 We have used eggs from birds kept under all sorts of 
 conditions. Birds that have run on the wide range, and 
 birds that for several years have been confined in very 
 small pens, also eggs from birds fed on i)ure grain and 
 birds that were fed on nothing but garbage. We have 
 not been able to detect any dilTerence in the fertility, and 
 vigor of the embryo in the eggs, as far as external condi- 
 tions and feeding of stock is concerned. More seems to 
 depend upon the vigor of the fowls, and especially the 
 males. Males should have a rest some time during the 
 year, or should be interchanged with others. This much, 
 however, is certain, that birds kept on a very large range 
 have the best chance of producing vigorous strong germs 
 in the eggs intended for hatching, but it must remain 
 for further experiment whether confining birds or diff- 
 erent methods of feeding affect the vigor of the embryo 
 in the eggs. 
 
CARE OP THE EGGS. 
 
 One of the first requirements for successful incubation 
 is the proper handling of the eggs. Eggs should be gath- 
 ered as soon as they are laid, and not exposed to the heat 
 or bright sun. They should be carefully placed in the 
 ordinary market egg cases, and should be kept in a cool 
 place (55 degrees), but under no circumstances should 
 they be exposed to draft of any kind. The fresher the 
 eggs are, the better they will hatch. 
 
 If it is expected to hatch every egg that is placed in 
 the incubator, no eggs over three days old should be 
 used. However, we have sometimes had reasonably good 
 results from eggs that were three and four weeks old. 
 There is a popular idea that eggs intended for hatching 
 should be turned every day. We doubt very much if this 
 does them any good. It is of much more importance to 
 handle the eggs very gently, for the jarring and shaking 
 of them is a heavy strain on the various membranes of 
 the egg. Violent shaking of the egg will destroy all its 
 possibility for hatching, and the less eggs intended for 
 hatching are handled, the better it is. 
 
 If eggs have become soiled, they should be washed, but 
 it would be better not to use any eggs that have been 
 washed, or subjected to any unnatural conditions in any 
 way. A clean egg gathered from the hen's nest and 
 placed immediately in the incubator has tremendous 
 chances over an egg that has been more or less abused. 
 
 Defective eggs, and those with round ridges through 
 the middle, or rough shells, or imperfectly formed shells 
 had better be discarded, as well as very small or very 
 large eggs. They will hatch very well at times, but 
 the chances are somewhat against them of producing a 
 perfect chick. Remember, do not expose your eggs to 
 the sun. Keep them cool, (about fifty or fifty-five de- 
 grees), but do not chill them, and above all handle them 
 very gently, and keep them out of the draft. 
 
 13 
 
THE PROCESS OF INCUBATION 
 
 THK KKillT TKMPKKATIKK l-'OK INCUUA.TION 
 
 We have made a large number of tests of the temper- 
 ature of eggs under the sitting hen. It is rather diffi- 
 cult to arrive at any exact temperature. The eggs on the 
 outer edges of the nest are usually considerably colder 
 than those in its centre, but as she shifts them around 
 a great deal, all the eggs receive the highest temper- 
 ature which she produces sometime or other during the 
 day. 
 
 If the thermometer be placed among the eggs, we have 
 not generally found it to register over 100 to 102 degrees. 
 If the thermometer be applied to the hen's body, we 
 have quite often found a temperature of 104 to 107 de- 
 grees. Great care must be exercised in taking the hen's 
 temperature, for as soon as she gets the least worried, her 
 temperature rises rapidly, and often in a few minutes reg- 
 isters lOS degrees or more. Even a non-broody hen, 
 with normal temperature of 98 will soon rise to 102 if 
 agitated. 
 
 The safest method of arriving at the temperature of in- 
 cubation under the hen is to thrust a sensitive ther- 
 mometer quickly into the middle of the egg taken from 
 the center of her nest. Numerous tests which we have 
 made in that way, always range closely between 102 and 
 104 degrees. Upon the whole, perhaps no better incu- 
 bating temperature can be found than 103 deegres. 
 
 In our practice the thermometer bulb is placed level 
 with the top of the eggs, and either left in contact with 
 the eggs, or very close to it, and the eggs are incubated 
 throughout the hatch from the beginning to the end 
 at 103 degrees. Under this temperature if the eggs are 
 fresh, chicks are almost always all hatched at the end 
 of the twentieth day. Sometimes, if weak, or old, they 
 will not hatch till the 21st day or later. 
 
 It is very important that the temperature be 103 de- 
 grees at the very beginning and should not drop below it 
 during the first six days. After being placed in the ma- 
 chine eggs should reach 103 in three to five hours 
 If it takes longer to reach the proper temperature, eggs 
 are sure to suffer. Nothing is so bad for eggs as say 80 
 to 85 degrees of heat for the first day. Some successful 
 hatchers even start at 106 and gradually drop down to 
 103. Watch your machine the first week as the apple of 
 your eye. After that you may sleep in peace. 
 
 Beginners are often needlessly worried if the tempera- 
 ture accidentally for a short time drops too low. Eggs 
 will successfully withstand quite a considerable amount 
 of low temperature, if it comes only once, but they will 
 
 14 
 
not stand endless see-saws of it. We have successfully 
 hatched eggs that accidentally were left out of the ma- 
 chine as long as from ten to twenty-four hours, and 
 reached a temperature as low as fifty degrees, during 
 part of the time. No bad effect seemed noticeable. The 
 chicks were perfect. But if there is a see-saw of tem- 
 perature, say even between 95 and 105 degrees, for sev- 
 eral days, the hatch is usually spoiled. 
 
 Overheating spoils the eggs much quicker than low 
 temperature. It depends a good deal on the age of the 
 embryo, how fatal overheating will prove. Up till the 
 6th day a temperature of 110 for several hours will 
 probably kill all the germs, though we have had them 
 withstand this for fifteen minutes or so, but where they 
 were exposed to this temperature for a longer period, 
 we always found all embryos dead. 
 
 We have one case on record, however, where the in- 
 cubator, by accident, had reached 115 degrees (end of 
 7th day of incubation), and stood at this probably for a 
 full hour or more. We only lost about 10% of embryos. 
 These all died within the next day. All the rest of the 
 embryos hatched perfectly, there were neither cripples 
 nor weaklings of any sort. 
 
 CRIPPLES. 
 
 Neither overheating nor chilling the eggs will cause 
 • cripples. We have never found any other cause of crip- 
 ples than drafts in the machine or too cold a bottom in 
 the nursery. We had one case where the incubator 
 hatched reasonably well, but 65% were cripples. It was 
 found the bottom of the nursery registered only 75 de- 
 grees. For the next hatch the nursery was filled with 
 straw and cotton batting, and no cripples appeared. 
 Perhaps the under side of the egg being so much colder, 
 retards the growth of the embroyo on that side, or chills 
 it, and thus deranges the normal development of the 
 chick. 
 
 It has been claimed that lack of turning causes crip- 
 ples, but we have not found it so. In one of our tests, 
 one half of the incubator was not turned at all during the 
 entire period of incubation and the other half was turned 
 three times a day. The half of the incubator which was 
 turned hatched normally. The half that was not turned 
 at all, hatched but very few chicks, but there were hardly 
 any cripples. Most of the chicks grew to maturity, but 
 did not get out. Many died during the second week, but 
 not a single germ was stuck to the shell. In the half 
 that was turned, there was one germ stuck to the shell. 
 Evidently turning or not turning has nothing to do with 
 germs sticking to the shell. Such germs are defective. 
 They have risen to the top and in some way become at- 
 tached to the shell, but probably not till after they 
 were dead. Their death is probably the cause of adher- 
 ing to the shell. At any rate, such could not have been 
 saved by turning. Ill-fitting doors will almost certainly 
 cause cripples in cold weather. 
 
 15 
 
TIKNING THE EGGS. 
 
 Our present practice is turning the eggs twice daily, 
 twelve hours apart, as nearly as possible. We have had 
 very successful hatches, however, where the eggs were 
 turned only once a day, and we have even had really 
 good hatches where the eggs were turned only five times 
 during the entire period of incubation, but upon the whole 
 our experience tends to show that turning twice daily 
 brings decidedly the best results, i)roviding a mechanical 
 turner is used. If the eggs cannot be turned in the ma- 
 chine without ojiening it, they should not be turned at all 
 for the first three days, and thereafter only once a day, 
 for only strong eggs will stand opening tne machine twice 
 a day, all the weaker ones will die in the shell or hatch 
 with protruding entrails, unabsorbed yolk, etc. 
 
 THE MECHANICAL TUKXER. 
 
 The mechanical turner was used years ago, but proved 
 a failure. For that reason it was one of the last things 
 we tried. But one day after a miserable hatch, such as 
 might even make a strong man almost come to tears, 
 we sat down dejectedly in the woodshed by the old hen, 
 trying to make up our mind whether to abandon the 
 whole wretched hatching business or to try it blindly once 
 more, we noticed that she shifted her eggs around every 
 20 minutes or half hour, but she did not get off the nest 
 to do it. She seemed to hug her eggs all the closer while 
 she turned them. This was a lesson, we had not watched 
 nature close enough in this respect. We built a turning 
 rack, so that we could turn eggs as did the hen, without 
 exposing them to the outer air, and in our very next hatch 
 we suddenly found ourselves much nearer the goal. The 
 easiest way to make such a mechanical turner is to use 
 thin strips of wood 14-inch thick and about % -inches 
 wide. Make a rack of these to fit closely into your in- 
 cubator tray after the manner of a ladder with the rungs 
 about 1 % inches apart. The side of your rack parallel 
 with the rungs should be two inches shorter than the 
 tray, so that this rack can slide forward and backward 
 upon the tray. The eggs are placed between the rungs 
 and when the rack is moved forward or backward all 
 the eggs are turned. The rungs of course are nailed so 
 that when the rack is placed upon the tray, the side or 
 the rungs is at right angles with the bottom of the tray. 
 A thin strip of wood nailed on the top of the wire-bot- 
 tom of tray on its sides makes a nice rail for the rack 
 to slide upon. Small holes can easily be bored through 
 the door of the incubator through which one or two 
 small wire hooks can be inserted to pull or push the turn- 
 ing rack forward or backward without opening the door 
 of the incubator. A plug must be inserted in the holes 
 after turning. This turning-rack takes up some space 
 and not as many eggs will go into the machine, as with- 
 out it, but you will get more chicks out of the machine 
 by using it . 
 
 16 
 
It seems that so simple a thing as this ought to have 
 been found out long ago, but apparently it was not. It 
 took us six weary years to discover this as well as other 
 things. The success and failure of a hatch sometimes de- 
 pends on very little things. There are a thousand wrong 
 ways to hatch eggs, we know a good many of them. 
 There is only one right way, we hope we have discovered 
 that in part at least. Remember, turn your eggs twice 
 a day, but never open your machine more than once a day. 
 Never! 
 
 TESTING EGG8. 
 
 In our practice the incubator is opened for the first 
 time on the 84th hour. The eggs are taken out and 
 tested. The tray is set on a table with a blanket placed 
 under the tray to protect the eggs from cold air circling 
 around underneath them. They are left exposed on top 
 We are using a 16 candle power electric light bulb en- 
 closed in a tin globe (can be made out of a baking powder 
 can), which has tv/o round openings one inch in diam- 
 eter. The eggs are held up two at a time, one against 
 each opening, when their contents may be clearly seen. 
 A darkened room must be used. When no electric light 
 is available, the best method is to make a tube about 
 fourteen inches long of black paper, roll it into funnel- 
 sliape with the smaller opening about 1 % inches in di- 
 ameter and the larger about six inches. Take an egg, 
 place it against the small end, hold up to sunlight, and 
 look through the large opening, the embryo may then be 
 clearly seen. Practice will soon teach to distinguish be- 
 tween the fertile and infertile egg. 
 
 Whatever method is used, care must be taken in hand- 
 ling the eggs very gently, and they should never be ex- 
 posed to strong light except for the briefest possible mo- 
 ment, nor should they be suddenly taken from a dark in- 
 cubator into the glaring sunlight. 
 
 It should be remembered that the hen generally hides 
 her nest, and eggs are never exposed to strong light. 
 While it is not known what damage might result from 
 exposure to strong light, it is not likely that nature has 
 made any provisions against it. Whatever is done with 
 eggs, be careful not to transgress upon nature's methods 
 
 COOLING THE EGGS. 
 
 We have not come to any conclusion as to the length 
 of time eggs should be cooled. The investigation of de- 
 sirable hatching conditions has been so exceedingly ted- 
 ious, and in order to arrive at certain results only one 
 thing can be taken up at a time. It is undoubtedly best to 
 follow the natural method as closely as possible, asthehen 
 does not leave the eggs more than once a day for over 
 five to fifteen minutes, and the cooling of the eggs for a 
 similar length of time probably comes as near being right 
 as possible. Under no conditions should the eggs be 
 cooled more than once a day, or be removed from the ma- 
 chine more than once in 24 hours. 
 
 17 
 
INFERTILE EGGS. 
 
 About the t'ounh day the embryo will appear in spider- 
 like form in the fertile egg, the red blood veins issuing 
 from the centre in all directions. This is the natural ap- 
 pearance of a vigorous germ. Where the veins have run 
 together into a bloody streak, the germ is dead. Experi- 
 ence alone will teach to distinguish between living and 
 dead germs during later periods of incubation. An 
 infertile egg shows perfectly clear before the tester, ex- 
 cept that in white-shelled eggs the yoke may be clearly 
 seen. 
 
 The object of testing eggs is to secure the Infertile 
 eggs. If eggs were not much more than three days old 
 when put in the machine, these infertiles that are perfect- 
 ly clear are practically as good as any other egg not over 
 seven days old. However, they should not be sold for 
 fresh eggs, but they are excellent for baking, cooking, 
 etc., and are decidedly superior to storage eggs. In 
 testing the eggs for fertility, they should be taken from 
 the incubator without turning, the germs will then all be 
 found lying on the upper side of the egg. They should 
 be held up to the light and if turned at all, it should 
 be done gently. 
 
 After all the infertiles have been removed, these latter 
 should be re-tested to get the perfectly good eggs. Hold 
 the egg up to the tester, then give it a quick jerking turn, 
 if the egg looks watery then, it is no longer good. It needs 
 experience to distinguish good from bad eggs. Break 
 open enough till you find out. 
 
 HOW TO TELL INFERTILE EGGS. 
 
 There is absolutely no way to distinguish a fertile from 
 an infertile egg without incubating it for some days. All 
 advertisements to this effect are frauds pure and simple. 
 Nor can the difference be found out by breaking open the 
 egg. There is a white spot, the germinal vesicle, in each 
 and every egg laid by hen or pullet, but many an amateur 
 cannot discover it, and he thinks what he does not see 
 is not there. This germinal vesicle looks precisely the 
 same to the naked eye in the impregnated or unlmpreg- 
 nated egg. Under the microscope the difference may 
 be seen. The germinal vesicle in the unimpregnated egg 
 is a simple cell, in the pregnated egg there is a ridge, or 
 row of cells, but several days, and staining fluids are 
 required to prepare an egg for microscopical examina- 
 tion. 
 
 VENTILATION OF EGGS IN THE INCUBATOR. 
 
 Perhaps there is no subject about which there are more 
 wild theories rampant than the question of ventilation. 
 As one reads the various incubator catalogs, he is sur- 
 prised at all the so-called wonderful discoveries each man- 
 ufacturer has made. Nevertheless, nobody ever seems 
 to have made any sort of an investigation that would 
 pass muster in a scientific laboratory. 
 
 18 
 
There has been a constant reiteration of the great ne- 
 cessity of fresh air, but nothing has proved so costly to 
 us as the apparent reasonableness of these theories. For 
 many years we believed this firmly and sacrificed about 
 $2000 worth of eggs to it. 
 
 Many an incubator have we built to improve ventila- 
 tion, but the results have been exceedingly disastrous. 
 In not a single case have we had a fair hatch where any 
 large amount of air was admitted into the machine 
 After some years of experimenting we finally invented a 
 device by which to test conveniently the relative amount 
 of carbonic acid gas under the hen and in incubators. 
 We were very greatly surprised as soon as we tested con- 
 ditions under the hen. We found the carbonic acid gas 
 under her very great indeed, much greater than in any 
 incubator. We also discovered at once that the incu- 
 bators with the least ventilation, showed much more car- 
 bonic acid gas than those pets of ours with much ventila- 
 tion. And the hatches from the incubators with poor 
 ventilation proved very, very much the best. 
 
 We also had one machine that had been a puzzle for 
 a long time. It was made in a very crude manner by 
 somebody and was a forbidding looking affair. We 
 had purchased it from one of our customers unseen, or 
 we certainly would not have bought it. But we had 
 bought several hatches of remarkably fine chicks from 
 this machine and so we risked it with eggs. We had 
 a fine hatch and it was run many times and never failed 
 us. The machine had a capacity of about 800 eggs and 
 had only one 1-inch opening for ventilation, which was 
 screened with two layers of burlap. When the carbonic 
 acid gas test was applied to this machine, we found it con- 
 tained by far the greatest amount of any machine in the 
 hatchery. So far it was hardly possible to doubt that 
 too much ventilattion was the cause of many failures. 
 We shut up the ventilators on our machines and stuffed 
 up all cracks and quite remarkable improvements appear- 
 ed at once. The chicks were much stronger and larger. 
 
 We thought perhaps the air-space surrounding the 
 eggs was too large, as even with our best incubators 
 we could not equal the hen in carbonic acid gas. We 
 then built an absolutely air-tight machine cf galvanized 
 iron throughout, that had almost no extra air space and 
 no nursery. This would even beat the hen on carbonic 
 acid gas, but we were never able to reduce its moisture 
 much below 90 on the wet bulb, and every hatch proved 
 a dismal failure. But undoubtedly not on account of too 
 much carbonic acid gas, but on account of too much 
 moisture. We found the woodencase with cloth screens 
 necessary to produce an incubator sufficiently dry when 
 all ventilators are closed. 
 
 We subjoin tables of the tests on carbonic acid gas 
 evolved both in incubators and under the hens. These 
 tables are the average of a large number of hatches, 
 where practically every fertile egg produced a perfect 
 chick. They are taken from hatches of eggs during the 
 
 19 
 
moulting season, when eggs are not naturally very vig- 
 orous. We early found that little is to be learned from 
 successful hatches from very vigorous eggs. They will 
 hatch anyway, and do not reveal the weak points of an 
 Incubator. Moreover, a hen was set each time as the 
 incubator was set. with eggs taken from the same lot, and 
 only such hatches are used in this table where both 
 the hen and incubator brought off hatches in every re- 
 spect alike, even to the relative weight of eggs and chicks. 
 Thus the utmost precaution has been taken to secure a 
 standard hatching table. We believe that conditions 
 which produce perfect chicks from coniiiaratively weaker 
 eggs, must be very nearly ideal. Such are rei)resented in 
 our table, so far as temperature, moisture, carbonic acid 
 gas and structure of machine is concerned. The values 
 obtained were from machines constructed like the one 
 shown on page 4. The table for hens are from a 
 Barred Rock and a ButT Orpington, sitting in roomy nests 
 with straw bottom. It will be seen that the amount of 
 carbonic acid gas varies more or less, as also does the 
 moisture, and accordingly when neither runs higher or 
 lower than any values given, no attention is paid to either 
 carbonic acid gas or moisture in our hatchery. It is not 
 necessary to have these the same every day so long as 
 they come reasonably near this standard. 
 
 STANDARD HATCHING TABLE FOR INCUBATORS. 
 
 D«y <rf_ I Temper I Cubic centi- I Carbonic I Wei 
 iDcubatioo J ^ature- | meter* of air I Acid Gai | Bu lb 
 
 1 103 ' 86' 
 
 Peroaat._ <A I Minulet Ess* 
 Humidity_ 1 were cooled 
 
 49 
 
 2 
 
 103 
 
 
 
 85 
 
 47 
 
 
 3 
 
 103 
 
 
 
 85 
 
 47 
 
 
 4 
 
 103 
 
 
 
 86 
 
 49 
 
 10 
 
 5 
 
 103 
 
 400 
 
 1 
 
 85 
 
 47 
 
 10 
 
 6 
 
 103 
 
 400 
 
 1 
 
 83 
 
 42 
 
 10 
 
 7 
 
 103 
 
 320 
 
 3 
 
 81 
 
 38 
 
 10 
 
 8 
 
 103 
 
 240 
 
 5 
 
 82 
 
 40 
 
 10 
 
 9 
 
 103 
 
 240 
 
 5 
 
 83 
 
 42 
 
 10 
 
 10 
 
 103 
 
 240 
 
 5 
 
 83 
 
 42 
 
 10 
 
 11 
 
 103 
 
 200 
 
 6 
 
 82 
 
 40 
 
 10 
 
 12 
 
 103 
 
 160 
 
 7 
 
 83 
 
 42 
 
 10 
 
 13 
 
 103 
 
 120 
 
 8 
 
 83 
 
 42 
 
 15 
 
 14 
 
 103 
 
 120 
 
 8 
 
 85 
 
 47 
 
 15 
 
 15 
 
 103 
 
 120 
 
 8 
 
 85 
 
 47 
 
 15 
 
 16 
 
 103 
 
 80 
 
 8 
 
 83 
 
 42 
 
 15 
 
 17 
 
 103 
 
 50 
 
 9 
 
 84 
 
 45 
 
 15 
 
 18 
 
 103 
 
 40 
 
 10 
 
 85 
 
 47 
 
 15 
 
 19 
 
 103 
 
 40 
 
 10 
 
 85 
 
 47 
 
 Esst pippins 
 
 20 
 
 103 
 
 50 
 
 9 
 
 92 
 
 68 
 
 Hatrb kalf ow 
 
 21 
 
 103 
 
 40 
 
 10 
 
 84 
 
 45 
 
 Hatch all oul 
 
 20 
 
RECORD OF TWO HENS 
 
 Oayo( 
 
 
 1 
 
 2 
 
 1 
 
 2 
 
 1 
 
 2 
 
 1 
 
 2 
 
 Incuba- 
 
 Vol. Ail 
 
 r,a« 
 
 Vol. Air 
 
 r.iii 
 
 Wrt 
 
 Mois- 
 
 Wet 
 
 Mois- 
 
 hen off 
 
 tion 
 
 
 
 
 
 
 Bulb 
 
 ture 
 
 Bulb 
 
 ture 
 
 ae& 
 
 1 
 
 
 
 
 
 
 
 
 
 X 
 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 
 246__ 
 
 5 
 
 206__ 
 
 6 
 
 
 
 
 
 
 
 4 
 
 
 240__ 
 
 5 
 
 80__ 
 
 9 
 
 85 
 
 47 
 
 
 
 X 
 
 X 
 
 5 
 
 :^ 
 
 240__ 
 
 5 
 
 120__ 
 
 8 
 
 
 
 
 
 X 
 
 
 6 
 
 i 
 
 160__ 
 
 7 
 
 80__ 
 
 9 
 
 
 
 86 
 
 49 
 
 
 
 7 
 
 
 160__ 
 
 7 
 
 80. _ 
 
 9 
 
 87 
 
 
 
 
 
 
 8 
 
 1 
 
 120__ 
 
 8 
 
 80__ 
 
 9 
 
 
 
 
 
 X 
 
 X 
 
 9 
 
 140__ 
 
 8^ 
 
 120__ 
 
 8 
 
 
 
 
 
 X 
 
 
 10 
 
 h-l 
 
 40__ 
 
 10 
 
 40_. 
 
 10 
 
 
 
 
 
 
 
 11 
 
 ^ 
 
 40__ 
 
 10 
 
 80. _ 
 
 9 
 
 
 
 87 
 
 
 
 X 
 
 12 
 
 o 
 
 30 _ 
 
 15 
 
 60__ 
 
 QV. 
 
 
 
 
 
 
 
 13 
 
 t-l 
 
 40__ 
 
 10 
 
 50__ 
 
 9^ 
 
 85 
 
 47 
 
 
 
 X 
 
 
 14 
 
 ►li- 
 
 40. _ 
 
 10 
 
 40__ 
 
 10 ' 
 
 
 
 84 
 
 45 
 
 
 X 
 
 15 
 
 
 30__ 
 
 15 
 
 80. _ 
 
 9 
 
 
 
 
 
 
 
 16 
 
 
 30__ 
 
 15 
 
 30__ 
 
 15 
 
 
 
 
 
 
 
 17 
 
 
 30^^ 
 
 15 
 
 20__ 
 
 18 
 
 
 
 
 
 X 
 
 X 
 
 18 
 
 
 30__ 
 20__ 
 
 15 
 20 
 
 20.- 
 20. . 
 
 18 
 20 
 
 
 
 -- 
 
 
 
 
 X 
 
 
 19 
 
 Chicks Pippins 
 
 
 20 
 
 
 20. 
 
 20 
 
 20- _ 
 
 20 
 
 
 
 AU through hatching 
 
 21 
 
 
 
 
 
 
 
 
 
 
 
 22 S 
 
 with brood of 
 s two days old 
 
 -50__ 
 
 9 
 
 
 The volume of air given in these tables are the num- 
 ber of cubic centimeters of incubator air which it took 
 to cloud one cubic centimeter of lime water. (The first 
 distinct clouding is the point used in the tables.) 
 These are exact measurements and should be used in fut- 
 ure investigations, to avoid the confusion of different 
 standards. The figures for volume of carbonic acid gas 
 are an arbitrary graphic representation of its density, as 
 indicated on the piston rod of our air pump. They show 
 relative, not actual values, but most admirably serve its 
 purpose to show the difference between hen and incu- 
 bator and different days of incubation. 
 
 The actual amount of carbonic acid gas present in an 
 incubator, it should be remembered, is also directly de- 
 pendent upon the number of fertile eggs in a given en- 
 closed space. These tables are not to be used for the 
 purpose of guiding ventilation, in the sense of admitting 
 air into the incubator in case there should be found more 
 gas than our tables show. Keep your incubator closed 
 tightly, no matter how much carbonic gas is found in 
 it. We, ourselves, have not been able to obtain any 
 higher values, and are of the opinion if we could secure 
 
 21 
 
a machine giving higher values, it would be still better, 
 for as will be seen from the tables giving the records of 
 hens, that the amount of carbonic acid gas is much 
 greater there. 
 
 It will also be seen that the amount of gas under the 
 hens is quite variable, depending upon how closely the 
 hen is setting. 
 
 We take it, that these investigations, prove, not act- 
 ually how much gas is necessary to hatch eggs, but that 
 absolutely confined air is of the very first importance in 
 an incubator. If you confine the air in your incubator 
 there will always be more or less carbonic acid gas 
 present. 
 
 On these measurements human breath shows clouding 
 at about 20 to 25 cubic centimeters, or 25 volumes of gas 
 on the figures for carbonic acid gas. 
 
 It is noticeable also that even the chicks two days old 
 under the hen's wing, live in the presence of much car- 
 bonic acid gas. 
 
 Notice also that these hens bringing off perfect hatches 
 only left the nest five or six times altogether. In cool- 
 ing eggs this fact should be taken into consideration. 
 
 <;p 
 
 3. P. Cook's Carbonic Acid Gas Test. Price, $5.00. 
 
 a, graduated piston rod (for each fifty cc. ) b, air 
 pump; c, rubber tube; d, glass tube; e, five cc graduate; 
 f, limewater. 
 
 22 
 
METHOD FOR TESTING CARBONIC ACID GAS. 
 
 Our method consists in withdrawing a certain portion 
 of air within the incubator taken directly above the eggs, 
 and about twelve inches from the front of the machine. 
 A small hole is bored through the frame of the door 
 about one quarter inch in diameter, through which a 
 small rubber tube with a glass end is introduced. This 
 rubber tube is attached to an air pump, holding from 
 250 to 300 cubic centimeters of air. The piston of the 
 pump is graduated for each 50 cubic centimeters. 
 
 After the air is withdrawn from the incubator, it is 
 passed through one-half centimeter of lime water, and the 
 point where the clouding of the lime water begins is 
 noted. 
 
 As is well known, this clouding is due to the amount 
 of carbonic acid gas, which has passed through the lime 
 water. The point at the piston is then read, which in- 
 dicates directly how many cubic centimeters of air have 
 passed through the lime water to effect the clouding. 
 
 The piston rod is graduated up-side-down, beginning 
 with 10 and ending with one, so as to indicate directly the 
 amount of carbonic acid gas. 
 
 For instance, if the first fifty cubic centimeters of air 
 effect the clouding of the one-half cubic centimeter of 
 lime water, the piston rod will stand at 10, which we 
 designate as 10 volumes of carbonic acid gas present in 
 the incubator. This is, of course, wholly arbitrary, but 
 it serves very well to give an indication of the relative 
 amount of the carbonic acid gas present. What this 
 measurement actually amounts to is this: The fifty 
 cubic centimeters of incubator air contains enough car- 
 bonic acid gas to cloud one-half cubic centimeters of 
 lime water, which is equal to 100 cubic centimeters of 
 incubator air clouding one cubic centimeter of lime water. 
 
 We suggest that all incubator tests on carbonic acid 
 gas to be made in the future, be made upon this measure- 
 ment, as it is very convenient indeed, and serves all prac- 
 tical purposes in the best possible way. Some unit of 
 measure will have to be decided upon, and as all our 
 tests have been made on this, it would only confuse mat- 
 ters if any additional standard of measurements were in- 
 troduced. 
 
 The lime water which we use is prepared in the ordin- 
 ary way, just taking a piece of unslaked lime and dissolv- 
 ing as much of it in water as the water will take up per- 
 fectly clear, and using the clear part of the water. We 
 use the ordinary five cubic centimeter graduate. The 
 whole outfit is sold for $5.00 to anyone who is interested 
 in these experiments. It is necessary to clean the 
 
 graduate after each test, as more or less clouding will 
 be effected, which will interfere with the reading. 
 
 If an ordinary rag will not clean it, use a drop of 
 hydrochloric acid, which will clean the graduate in- 
 stantly, and it should be well rinsed after cleansing. 
 
 In all our tests the air was not withdrawn from the 
 incubator until it had been closed for 2 4 hours. 
 
 23 
 
THE MOISTURE PRORLEM, 
 
 There is uo end to the theories about moisture in an 
 incubator. There seems to be an almost universal o[)in- 
 ion that eggs will be helped by being sprinkled, or by 
 filling the incubator by some means with moisture. 
 
 Undoubtedly the moisture problem is a very important 
 one in artificial incubation, and it is by far the most 
 difficult of solution. It is comparatively easy to deter- 
 mine the relative amount of carbonic acid gas under a 
 setting hen, and it is also comparatively easy to secure 
 something of a corresponding amount of this gas in an 
 incubator by reducing the air space surrounding the eggs, 
 but with the moisture problem it is different. It is al- 
 most imi)ossible to find out the relative amount of mois- 
 ture surrounding the eggs under a setting hen. The 
 space is so very small that it is almost impossible to make 
 any test. The wet bulb thermometer is practically inap- 
 plicable here. The amount of moisture introduced by 
 the wet bulb would interfere with any correct results of 
 a test. 
 
 About the only other method available is the use of the 
 spiral hygrometers, which are very unreliable at best. 
 We have made hundreds of tests of setting hens, using a 
 spiral hygrometer, placing it as carefully as possible, and 
 after reading it transferring it to an incubator, and intro- 
 ducing moisture into the compartment, or withdrawing It 
 until we found a corresponding reading, and then compar- 
 ing it with our wet bulb instrument. 
 
 There would be only one other way of measuring the 
 moisture under the setting hen, and that would be by 
 withdrawing a small portion of air, and by analysis de- 
 termining the actual percentage of moisture present in 
 it. For this we did not possess the necessary instru- 
 ments, and it is very doubtful if it would be of very much 
 value. The results which we have obtained have been 
 variable indeed, ranging as low as 3.5',; of humidity, and 
 as high as 60';{. It has been impossible to get almost 
 any two readings alike. Perhaps the only actual result 
 that is dependable is the fact that in all cases the hu- 
 midity of the air surrounding the eggs under the hen 
 was considerably drier than the outside air. 
 
 It was also found that the amount of humidity under 
 the hen bears no corresponding relation to the humidity 
 in the outside air. Some of our tests of hens setting 
 practically out of doors, in rainy weather, with the rain 
 dropping over their wings, still showed only about 40° 
 of humidity over the eggs. But to repeat, none of the 
 tests made can be regarded as in any sense absolutely 
 accurate, so we have no clue as far as the hen is con- 
 cerned, what the amount of moisture should be sur- 
 rounding the eggs. Perhaps the safest way is to re- 
 gard the lowest reading the most accurate, as nearly all 
 instruments register higher than actual humidity. 
 
 When it comes to the incubator it is easy enough to 
 determine the relative humidity inside the egg chamber. 
 All that is needed is a reliable wet bulb thermometer. 
 
 24 
 
Place it carefully, and read the difference between the 
 dry thermometer, and the wet bulb thermometer, and the 
 amount of relative humidity can be readily determined 
 by the use of psychro-metrical tables published by the 
 United States weather bureau. (A number of so called 
 incubator hygrometers are on the market, which pretend 
 to give a direct reading of the humidity in the egg cham- 
 ber, but these cannot be used for anything like accurate 
 work. Some of them do not read low enough, and it is 
 doubtful if others are sufficiently accurate. Any hygro- 
 meter that does not read as low as 35° is worthless for 
 incubator use, and should not be sold for that purpose.) 
 
 For all practical purposes it is much simpler to disre- 
 gard the actual relative humidity, but carefully note the 
 depression of the wet bulb thermometer. In that way 
 all confusion and difficulty is avoided. 
 
 The only method open to determine the right amount 
 of moisture for successful incubation, is by repeated ex- 
 periments. Our experiments in this line have continued 
 for over six years, and hundreds of hatches have been 
 carefully noted. We have never found a good hatch 
 unless the air in the incubator was comparatively dry. 
 The percentage of about 40° or 45° humidity seems to 
 give the best results, which is equal to a depression of 
 about 18° to 20° on the wet bulb thermometer. Where 
 it is possible we prefer to use 20° of depression for 
 hatching, i. e., 83° on the wet bulb. We have had uni- 
 formly good results at this point, provided all other 
 things are right. There is no doubt that a great many 
 incubators, and a great many hatches fail because it is 
 impossible to get the air dry enough. Of course, on the 
 other hand many hatches are spoiled by the air being too 
 dry on account of the excessive ventilation within the 
 incubator chamber. But it was found in our other ex- 
 periments that there must be practically no ventilation o' 
 any kind in the incubator chamber, and the air surround- 
 ing the eggs must remain perfectly quiet in order to main- 
 tain sufficient carbonic acid gas and prevent the formation 
 of cripples. This makes the moisture problem a most 
 difficult one. Incubators will act as contrary as anything 
 that can be imagined in this respect. 
 
 The problem in incubation is to get the air within the 
 egg chamber to run about 83°, wet bulb, without ventila- 
 tion of any sort. Where this cannot be accomplished the 
 hatch will be more or less a failure. Some incubators 
 we have had we simply could not use at all. Others of 
 identically the same make worked without any trouble. 
 Only a very few that we found needed artificial moisture, 
 when the machine had been made practically air tight. 
 
 One of our large machines was a constant puzzle to us. 
 It contained eight compartments holding 2 000 eggs. 
 The compartments are all built identically alike. They 
 are all heated in the same manner by one hot water sys- 
 tem. They all show the same temperature yet one com- 
 partment runs 2 0% higher in moisture than all the others, 
 and consequently we cannot use that compartment. We 
 
 25 
 
have been unable to determine any reason whatever for 
 this difference. There are certain seasons of the year, 
 however, when all the compartments run alike, and we 
 can use the whole machine. This is simply one of the 
 instances of the many queer actions with which incu- 
 bators confront us. 
 
 We find that a space about twelve inches high from the 
 bottom of the machine to the top is necessary to give suffi- 
 cient dryness of the air, which has to take up of course 
 the evaporation of the moisture from the egg, and still not 
 become too highly saturated with moisture. 
 
 We have sometimes found it quite an improvement to 
 slip a diaphragm, made of thin muslin, between the eggs, 
 and the hot water pipes, thus making two compartments 
 in the machine. The diaphragm should be close to the 
 pipes. Small openings may then be made through the 
 top of the machine into this upper compartment, say one 
 or more half inch holes for every 250 eggs. This has 
 a tendency to cause a very, very slow movement of the 
 air, and as more heat is needed to heat up the incubator 
 through this diaphragm, there is more dry air in the ma- 
 chine than can otherwise be secured. It seems the small 
 opening helps to dry out the air without appreciably af- 
 fecting the air below the diaphragm. 
 
 In smaller machines we have found a rather effective 
 way in allowing hot air to circulate around the heater, and 
 allowing it to open into the upper compartment of the 
 machine. This makes the circulation of the air much 
 slower since it has no outlet, but it seems to secure the 
 dry atmosphere, which is so very essential in the egg 
 chamber. 
 
 The moisture in the air of the incubator room has no 
 effect on the eggs in the machine. An incubator with 
 ventilators open will usually register much drier on blus- 
 tering rainy days than on hot, dry, or sultry days. In 
 warm weather the incubator ventilators do not work at 
 any rate, for if there is not much difference in the tem- 
 perature outside the machine, no air will pass through. 
 It may be given as a safe rule never to put water in an 
 incubator, on hot sultry days. If ever any moisture is 
 needed, it is in winter, or on windy days. Those are 
 the times when the incubator is actually too dry. This 
 will sound strange, to the inexperienced, but place a re- 
 liable hygrometer in the incubator on hot, dry days, and 
 you will find a very high humidity. The opposite wnll 
 be found on cold days, even if they are rainy. More 
 air is sucked through the incubator on cold, windy and 
 blustering days, which causes it to be excessively dry. 
 Sprinkling the floor of the incubator room has not the 
 slightest effect on the moisture within the machine. The 
 effect of too much moisture in the incubator will be that 
 many chicks are dead in the shell, as many as one half 
 or more sometimes. 
 
 A rough distinction may be made in this way: If the 
 chicks that hatch are scrawny little things with protrud- 
 ing entrails, or unabsorbed yolk, there was too much yen- 
 
 26 
 
tilation. If the chicks that hatch are fairly good and 
 large in size, the chicks dying in the shells is due to too 
 much moisture. Both faults cause chicks to die in the 
 shell, and both must be avoided. However, it is safe 
 to say ten times as many chicks die in the shells from 
 too high humidity, i. e., too much moisture, than for lack 
 of it. 
 
 If moisture is actually needed, the best way to intro- 
 duce it is a wet sponge placed on the eggs. Water pans 
 may be placed in the bottom, but this does not usually 
 have much eifect. 
 
 2. P. Cook's 
 
 simplified 
 Hygrometer. 
 
 Price, $1.00. 
 
 B Wei- Bulb P5>jLhro>^itle«- 
 
 p. Cook's continuous reading 
 Hygrometer. Price, $3.00. 
 
 DIRECTIONS FOR USING P. COOK'S HYGROMETER. 
 
 Our hygrometer consists of two accurate thermometers, 
 one of which has a muslin wick connected with a water 
 cistern, attached to it. The whole instrument is placed 
 in the machine like an ordinary thermometer. The evap- 
 oration of water from the wick around the bulb of one 
 thermometer causes this bulb to cool in proportion to the 
 amount of evaporation. The drier the air in the incu- 
 bator, the more rapidly will it evaporate water from 
 the wick and thus cause the wet bulb to read lower than 
 the dry bulb thermometer. Indirectly, the difference be- 
 tween the two thermometers indicates the dryness of the 
 air. This is the method used in the U. S. Weather Bu- 
 reau, and it has published elaborate tables from which 
 
 27 
 
the relative per cent of humidity can be learned if once 
 the depression of the wet bulb thermometer is known. 
 We print here a part of these tables as far as they are 
 of use for incubator purposes. For instance, if the dry 
 bulb stands at 103 and the wet bulb at .S3, there is twenty 
 degrees difference, i. e., there is twenty degrees depres- 
 sion on the wet bulb. The wet bulb thermometer is 
 technically called a psychrometer. From the table it 
 will be seen that there is 42 ])er cent relative humidity 
 in this case. Or if the dry bulb registers 100 degrees and 
 the Psychrometer S2 degrees, there is IS degrees depres- 
 sion, and it is found from the table that in this case there 
 is 46 per cent humidity. 
 
 rSY( H ROMKTER TABLES. 
 
 iture of 
 
 rmometei 
 
 
 Deiiise* of DepreuioQ of Psychi otnetet 
 
 1' 
 
 16 
 
 17 
 
 18 19 
 
 20 
 
 21 22 
 
 98 
 100 
 102 
 
 
 50 
 51 
 52 
 
 48 
 49 
 49 
 
 45 
 46 
 47 
 
 43 
 44 
 45 
 
 40 38 
 
 41 39 
 
 42 40 
 
 36 
 37 
 38 
 
 B r 
 
 103 
 
 52 
 
 53 
 53 
 
 49 
 
 50 
 51 
 
 47 
 
 45 
 
 42 40 
 
 38 
 
 
 104 
 106 
 
 48 
 49 
 
 46 
 46 
 
 43 
 44 
 
 41 
 
 42 
 
 39 
 
 40 
 
 
 For practical purposes it is much easier, however, to 
 disregard these moisture percentages. It is enough to 
 know that when your thermometer reads 103 degrees and 
 the Psychrometer 83 to 85, your machine is working 
 properly and no further attention need be paid to it. 
 
 Ordinarily, if an incubator is once started righi, and 
 our other instructions for closing the ventilators, etc., 
 have been followed, there will be no need to use a hygro- 
 meter, as the moisture does not generally vary much dur- 
 ing a hatch. Nevertheless, it will soon pay to be in 
 possession of a hygrometer, but as our larger instrument 
 costs three dollars, it is too costly for the man who has 
 only a small machine. We have, therefore, designed a 
 much cheaper instrument, which is just as reliable, but 
 takes a little more trouble to use it. This is simply an 
 accurate Thermometer reading down to 75 degrees. A 
 thin piece of muslin is tied around the bulb, this is 
 dipped in luke-warm water and then inserted into the 
 incubator, through a hole bored in the door. It is left 
 there for ten minutes and then partly pulled out to see 
 how low it reads. Its lowest reading, just before the 
 muslin is completely dried out is its correct reading. A 
 number of readings should be taken, the lowest one is the 
 most correct. The incubator should not be opened be- 
 
 28 
 
fore inserting the Psychrometer. Remember the differ- 
 ence between it and your thermometer indicates the mois- 
 ture. If your incubator stands at only 100 degrees, then 
 80 degrees on the Psychrometer indicates proper hatch- 
 ing humidity. It is twenty degrees difference that is 
 required. Use your table unless your incubator stands 
 at 103 degrees. The simplified instrument is sold for 
 $1.00, and will be found a most excellent help. Only one 
 instrument is needed no matter how many incubators 
 are used, as moisture does not need to be taken oftener 
 than in the beginning and two or three times during the 
 hatch. 
 
 We are aware that these directions require much drier 
 air thany many manufacturers advise, but we have in- 
 quired among many hatchers and we have not heard of 
 one of them that has succeeded in securing good hatches 
 at any other percentages the great claims of some 
 
 hygrometer makers notwithstanding. It should be remem- 
 bered however, that our figures are for incubators with 
 perfectly still air, i. e., without any ventilation. Still 
 air is not nearly as drying as air in motion. 
 
 From our standard hatching table it will be seen that 
 during the exclusion of the chicks we allow 9 2 on the 
 Psychrometer. This is normal and need not be changed 
 unless chicks are breathing heavily or standing with their 
 mouths open. This indicates too much moisture, as often 
 as too much heat. Ventilators must then be opened, or 
 if the machine has no ventilators, open the doors for a 
 minute and let the moisture escape. As soon as the 
 hatch is over, see that enough air is admitted into the 
 machine to dry out and fluff up the chicks properly. 
 
 Sprinkling the eggs will never do them any good; its 
 only effect is to chill them, and if they hatch at all, they 
 hatch in spite of it. In fact nothing that is done to the 
 eggs for a few minutes during the last week, helps tliem 
 in any way. We seldom ever find any need of moisture 
 during hatching time, only if something is seriously 
 wrong with the incubator moisture will help to over- 
 come its defects. Shut your machine tight until pipping 
 time, and do not open it till chicks begin to show signs 
 of the need of more air. 
 
 Some Tyi)ical Tests of Moisture Under Setting Hen. 
 
 7 a. m. Outside air near hen's nest temperature 5 2 
 degrees, moisture full saturation or 100 per cent, moisture 
 under the hen, 49 per cent. 12, noon, temperature out- 
 side, 74 degrees; moisture 5 8 per cent; moisture under 
 the hen, 40 per cent. 5 p. m. Temperature 66, moisture 
 61 per cent. Moisture under the hen 40 per cent. In all 
 the numerous tests we have made, we always found much 
 less moisture under the hen than in the air around her. 
 As she heats the air in her nest, it would naturally reg- 
 ister drier than the outside air, unless she supplied mois- 
 ture from her body, but as all tests show this is not the 
 
 29 
 
case. The hen does not sweat through her skin and it 
 seems that her feathers asbsorb the evaporation from 
 the eggs. We had one White Rock hen sitting on damp 
 ground and the moisture under her always ran between 
 (>0 to 65 per cent, but all the germs rotted in the shell, 
 only three lived till the 21st day, but did not hatch. The 
 other tests above given are from hens that brought oCf 
 normal hatches. 
 
 Where we made daily tests for moisture, the hens al- 
 ways brought off poor hatches, due no doubt to disturb- 
 ing the hens too much. 
 
 HELPING CHICKS OUT OP THE SHELL. 
 
 There is little use to help chicks out of the shell when 
 they have not been properly incubated, but in the moult- 
 ing season we have sometimes found that the stragglers 
 can be helped to advantage. A chick should never be 
 helped too early, and unless it is plump and in every re- 
 spect perfect when helped out, it is not worth anything 
 In the time that eggs are naturally fertile, all chicks will 
 usually pop out without any help. Chicks too weak to 
 get out then is a sure indication of faulty incubation. No 
 chicks should be helped out until the hatch is nearly 
 over. 
 
 TYPICAL WEIGHTS OF A GOOD HATCH. 
 
 100 Fresh eggs, 11% lbs. 
 100 clear eggs 10 ibs., 6 oz. (1.5 days in incubator), 
 at 85 Psychrometer reading.) 
 
 100 chicks 8 lbs., 1 oz. 
 GOOD HATCHES ATTRIBVTED TO WUONG CAUSES. 
 
 Here it is well to point out that frequently good hatches 
 are attributed to wrong causes. Mr. "A" puts a pan of 
 water under his eggs, the last few days, or sprinkles 
 them or gives more ventilation, etc., and has a good 
 hatch. He concludes this is the thing to do. But it may 
 have had nothing whatever to do with the good hatch. 
 The fact is that strong eggs hatch well in spite of a 
 good many things. We dropped a tray of eggs once. 
 Two-thirds of the eggs cracked. (16th day of incuba- 
 tion.) We patched them up with celloidin and they 
 all produced remarkably strong chicks. Nevertheless, 
 cracking eggs is not the best way to hatch them. It 
 should be remembered, the critical period of incubation 
 are the first six days, and it may almost be said, that 
 it does not matter what happens after that. Certainly 
 eggs will stand quite a lot of abuse after that and still 
 hatch well. So far as ventilation is concerned, it may 
 be said that most arrangements do not work, which is 
 their recommendation. If the ventilators of the incu- 
 bator actually get to work, then they produce mischief. 
 If the incubator is placed in a room where the air is 
 still, there is but very little ventilation going on inside 
 the machine, but if the air of the room gets in motion, 
 
 30 
 
it will be sucked through the ventilators of the incubator, 
 and a spoiled hatch will follow. Too much ventilation 
 produces small, scrawny chicks with protruding bowels, 
 etc. A spoiled hatch from too much ventilation is about 
 the sickliest sight imaginable. The glowing claims of 
 incubator manufacturers that their machines change the 
 air ever so often, are fortunately not often true, but 
 when they are true their machines fail to hatch. 
 
 It is not known whether the amount of carbonic acid 
 gas has anything to do directly with hatching, for it 
 varies greatly under different hens. It may be that all 
 that is required is absolutely still air in the incubator. 
 In still air the gases do not diffuse very readily. We 
 found in one machine that had eggs only on one tray, 
 twice as much carbonic acid gas as on the other tray 
 without eggs. As a rule, there is a little more at the 
 bottom than near the top of the machine, which is 
 natural, since the carbonic acid gas is heavier than air. 
 The fact remains, however, that eggs under the hen are 
 incubated under the pressure of a very large amount of 
 carbonic acid gas. This was found true even of a tiny 
 bantam hen that weighed only about one pound, but the 
 percentage of carbonic acid gas under her was as great 
 as under the large hens. This proves conclusively, that 
 there is no so-called ventilation under the hen, nor any 
 diffusion of the natural gases, or the carbonic acid gas 
 would have been carried away. 
 
 The chief value of these measurements, as we regard 
 it, is in the fact that they pointed out the right way to 
 build an incubator, i. e., one that surrounds the eggs with 
 still air, and thus produces conditions similar to those 
 under the hen. There is, of course, no reason to believe 
 that carbonic acid gas itself helps the hatching. It is a 
 waste product of the respiration of the embryo but em- 
 bryonic respiration is a decidedly different process from 
 respiration of the full grown hen, and a large amount 
 of carbonic acid gas may not be detrimental, or it may 
 have a sort of symbiotic action, but such consideration 
 we may leave to the professional biologist. 
 
 Ordinarily the user of the incubator need not test the 
 carbonic acid gas. Let him follow our directions in con- 
 structing his machine, and he will not generally experi- 
 ence trouble. However, the carbonic acid test is the only 
 reliable guide to the ventilation. 
 
 METHOD OF HATCHING IN P. COOK'S MAMMOTH 
 HATCHERY. 
 
 (The method here given has reference to incubators 
 sold commonly to the public, as this will be of great use 
 to persons who already possess incubators. The prin- 
 ciple is exactly the same as that followed in Mr. Cook's 
 own mammoth machines.) 
 
 The first thing that is done is to see that the incubator 
 is in good working order, the lamp burning properly and 
 lamp fountain not leaking and thermostat in perfect 
 
 31 
 
order. Then the door Is examined, and if it does not 
 fit air-tight, strips of felt are nailed around the edges, 
 so as to make it fit tight. One or two layers of burlap 
 or cotton batting are placed in the bottom of the ma- 
 chine to make it warm enough below the eggs. 
 
 The temperature at the bottom of the incubator should 
 never be allowed to fall much below 90 degrees. If it 
 is colder than that cripples are sure to result. If the 
 machine has nursery diawers, it is best to fill these up 
 with straw or cotton for the first two weeks at least. If 
 the machine has no nursery the temperature at the bot- 
 tom of the egg-tray should be at least 100 degrees. 
 
 When the machine is heated up, the thermometer is 
 placed in position where the top of the eggs would come 
 and the regulator adjusted to hold the machine at 103 
 degrees. The machine is kept going for a day or so with 
 ventilators open in order to dry it out. Then a hygro- 
 meter is also placed into it and watched till it sinks to 
 83 degrees. It may take several days to dry out the ma- 
 chine sufficiently. Then the ventilators are all closed 
 and the hygrometer read again. If it stands between SO 
 and 83 degrees, it is all right. If it stands above that, 
 the machine must be further dried out. There is not 
 much probability of a good hatch if the hygrometer at 
 the beginning of a hatch remains as high as S7 for more 
 than a day. 
 
 We had to run one machine for three weeks, before it 
 became dry enough for hatching. If you cannot make 
 your machine dry enough do not waste your eggs on it. 
 We have never come across a machine too dry, if all its 
 ventilators are closed. 
 
 Next the egg trays are taken and fitted with a me- 
 chanical turning rack as described elsewhere. The eggs 
 are placed on the tray with the turning rack in position. 
 They are laid flat on the side and not crowded. You can 
 get more eggs into the machine by standing them on 
 edge, or even by doubling them up, and the strong 
 eggs will hatch that way, but the weaker ones will die 
 in the shell. But remember, what is not good for the 
 weaker eggs, is no benefit to the stronger ones either. Do 
 not begin the poultry business by abusing your chicks 
 before they are born. It is knocking your profits with a 
 club on the head. 
 
 When the eggs are on the tray, thermometer and hygro- 
 meter are then placed in position and all outgoing venti- 
 lators are shut tightly. The best way to do this is to 
 stuff a tuft of cotton into the holes. It need not be 
 stuffed very tightly. Those machines that have the air 
 intake over the lamp or around the heater, need only 
 to have the outlets closed, for as soon as these are closed 
 no more air passes through them into the machine. On 
 other machines all ventilators must be closeor. 
 
 The eggs are turned by the mechanical turner after 
 six hours and after that every twelve hours apart, but 
 under no conditions must the machine be opened for the 
 first 72 to S4 hours. 
 
 32 
 
On the morning of the fourth day the incubator is 
 opened for the first time and the eggs are talten out 
 and aired for about ten minutes. They are also tested 
 for infertiles at this same time. Then the eggs are re- 
 turned to the incubator and turned mechanically twelve 
 hours after this without opening the machine. At the 
 next twelve hours the eggs are aired again for ten minutes 
 and so on till the twelfth day. After that they are aired 
 15 minutes, but never under any circumstances is the 
 machine opened more than once a day. This method, 
 ventilators closed, eggs aired only once a day, but turned 
 twice daily, and 83 degrees on the psychrometer, we 
 have found an unfailing cure for chicks dying in the 
 shell. But no one of these details must be omitted, or 
 the hatch may be spoiled. 
 
 On the 18th day the machine is closed, but small ven- 
 tilators may be left open, if your incubator room is free 
 from drafts. There will be no trouble, if these directions 
 have been followed, with chicks getting out of the shell. 
 There will be a downy lot of fine fluffy balls, as lively as 
 can be wished in your machine next morning. 
 
 In one respect nothing is so important as this closing 
 of the ventilators, especially if your incubator stands 
 in a room that has the least draft in it. Eggs will not 
 hatch to the best advantage except in absolutely still air. 
 For that reason taking eggs out of an incubator twice 
 a day is detrimental. Only the strong eggs will stand 
 it, the weaker ones will die in the shell. Do not worry 
 about the need of fresh air. There is rar more oxygen 
 in the incubator than the eggs will ever need, as is shown 
 conclusively by the carbonic acid gas test. It is true the 
 carbonic acid gas may be a very variable quantity, de- 
 pending upon the number of eggs in the incubator, etc., 
 but the still air is the thing of highest importance. We 
 know of hundreds of incubators that miserably failed to 
 hatch with the manufacturer's fresh air directions v\rhich 
 became first-class hatchers by simply nailing up the ven- 
 tilators and using a mechanical turning tray. 
 
 During the proper season of the year we find that gen- 
 erally every germ alive at the 17th day hatches a perfect 
 chick. Even in the molting period we have had many 
 perfect hatches by this method, but occasionally some 
 chicks die in the shell then, however, we seldom find over 
 ten per cent of dead chicks even at that time. Of course 
 no account is taken of germs that die before the seven- 
 teenth day. Sometimes there are many of these, but the 
 fault lies with the eggs in such cases and neither hen nor 
 incubator could hatch them. 
 
 HATCHABLE EGGS. 
 
 There is a large difference of opinion as to which is 
 to be considered a fertile egg. Breeders in selling eggs 
 usually follow the practice of guaranteeing a certain 
 percentage of fertile eggs, meaning that they will replace 
 any perfectly clear eggs below their guarantee. There 
 are, however, always a certain number of eggs with im- 
 
 33 
 
perfect germs or weak germs, or whatever they may be 
 called. None of these imperfect germs can be expected 
 to hatch. Neither hen nor incubator could do anything; 
 with them. Some of these germs do not aevelop any 
 farther than simply to make a bloody streak through 
 the yolk of the egg. Others grow longer. Some live as 
 long as the 13th and 14th day. In all these cases the 
 germ of the egg has been faulty, and it is impossible to 
 hatch such eggs. The proportion of these eggs depends 
 upon the vigor of the fowls, and to some extent also on 
 the season of the year. It is a good plan to test all the 
 eggs in an incubator on the 17th day. All of the em- 
 bryos dead at that time should be removed. If all the 
 chicks alive in the shell on the 17th day hatch, the hatch 
 may be called a perfect hatch, as that is all that can pos- 
 sibly be expected to hatch. But the great great difficulty 
 with incubators has been that the chicks die in the shell 
 after the 17th day. If any large proportion of chicks die 
 in the shell after the 17th day we consider it the fault 
 of the incubators, not of the eggs. After chicks have been 
 developed up to that stage they would probably hatch 
 if they had been incubated right. Our experience has 
 been that if everything has been right during 
 the period of incubation practically all the chicks alive 
 at the end of the 17th day will hatch. 
 
 MAMMOTH AND COMPARTMENT MACHINES. 
 
 We have spent a great deal of money in the attempt 
 to build a large compartment machine heated by only 
 one heater and capable of continuous hatcning. Such 
 a machine is evidently very desirable for a large hatch- 
 ing plant, but we have met with only moderate success 
 in this direction. It is easy enough to construct a ma- 
 chine with any number of compartments to hatch prop- 
 erly if the entire machine is filled with eggs at the same 
 time. Then all the compartments require the same 
 amount of heat and the entire machine can easily be 
 regulated by one thermostat. But difficulty arises when 
 eggs of different periods of incubation are placed in dif- 
 ferent compartments. The eggs much ahead generate 
 a good deal of their own heat and have to be in cooler 
 compartments. It is very diflicult to remove surplus heat 
 from such compartments without interfering with the 
 necessary moisture and carbonic acid gas conditions. The 
 easiest way to remove heat from a compartment would 
 be by letting it escape through ventilators, but this is 
 not permissable, for ventilation spoils the hatch. Stop 
 cocks or other methods must be used, which involve a 
 great deal of expense. It can no doubt be done, but we 
 have abandoned it for our own use. We have found 
 it much the cheaper method to build different incu- 
 bators. One machine can be used for the first week, an- 
 other for the second and a special machine can be built 
 for the last week with conveniences to take care of 
 the chicks for hatching. 
 
 34 
 
Our machines are 22 feet long and four feet wide and 
 in this size we have found no need for more than one 
 thermostat for each machine. Each machine is built 
 with eight compartments independent of each other. 
 
 NURSERIES. 
 
 We have used machines with nurseries in nearly all 
 our experiments. We do not know of how much real ad- 
 vantage they are. In a big hatch chicks seem to have a lit- 
 tle more elbow room as they are away from the shells. 
 Many machines are made with drawers, but these are 
 not always an advantage. If a machine is made with 
 drawers, it should be so made that the egg tray is placed 
 on the drawer and always comes out with it. If the 
 drawers are made to slide in under the tray, there is 
 always trouble. As soon as the drawer is pulled out 
 a number of chicks will jump over the back of the drawer 
 and others raise their head and you can neither shut nor 
 open the machine or get the chicks. We prefer no draw- 
 ers at all unless the egg tray comes out with the drawer. 
 
 DISINFECTING INCUBATOR. 
 
 At least every third hatch an incubator should be 
 thoroughly disinfected. The trays and bottom should be 
 thoroughly cleansed'. They can be washed with almost any 
 good disinfecting fluid or sulphur may be burned in it. 
 This last is the most effective method, but it will require 
 some days of airing before you can get the sulphur out 
 again. However, it is not necessary to get all the sulphur 
 smell out. We have had good hatches with the sulphur 
 smelling strongly all during the incubation. 
 
 The incubator is a splendid hatcher of all kinds of 
 germs and white diarrhea may be caught in the incubator. 
 
 On the other hand, the incubator should not be blamed 
 for chicks dying after they are some days old. If the 
 chicks are big and strong when hatched, you may be as- 
 sured that the incubator has done its part. After that 
 the fault lies with the brooding. 
 
 INCUBATOR HOUSES AND CELLARS. 
 
 Incubator may be placed in any room that will shel- 
 ter it, but a basement or cellar that is light and cheery, 
 and not too damp is very desirable, for the temperature 
 of such a place is not subject to as much variation as an 
 ordinary room. The most desirable temperature for an 
 incubator room is between sixty and seventy degrees. The 
 most important item, however, is, that it be well venti- 
 lated, but absolutely free from draft. Nothing works 
 so much mischief in an incubator room as drafts. In a 
 perfectly quiet room it is not always necessary to resort 
 to the mechanical turning tray. Eggs will fairly well 
 
 35 
 
^ad 14 1911 
 
 stand opening the machine twice a day for turning, only 
 for the one turning the eggs must be returned as soon as 
 possible to the machine. But even in the best incubator 
 room a strict adherence to our method will be found to 
 pay well. 
 
 A cellar three feet deep with cement floor and walls 
 and the rest of the building above ground, is the ideal for 
 an incubator house. It should be kei)t dry. Never 
 sprinkle the floor. 
 
 It is immaterial whether lamps, gas or coal, etc., is 
 used for heating incubators, but the fumes should be 
 carried off through chimneys. 
 
 CHICKS DYING IN KKOODEK. 
 
 It is not always easy to raise a big flock of chicks artifi- 
 cially, and while it does not belong here, we may as well 
 point out one great means of saving chicks. People have 
 become so accustomed to the necessity of disinfection 
 that they believe if they could only kill all the germs, 
 their chicks would do well, but they forget that there 
 are as many if not more, beneficial germs as there are 
 disease germs. Disinfection kills both the good and bad 
 germs. The real remedy is not always more disinfec- 
 tion, but better natural conditions for the chick. Prof. 
 Metchnikoff, head of the Pasteur Institute in Paris 
 hatched and tried to rear chicks under absolutely germ- 
 proof conditions, but found that his chicks would dwindle 
 away and die in a few weeks. Afterwards he allowed 
 his chicks to come into contact freely with the ordi- 
 nary dunghill bacteria and they were thriving as they 
 should. The intestinal canal is inhabited by a number 
 of bacteria that aid materially in digestion, and the en- 
 tire absence of these causes many chicks to die appar- 
 ently without any cause. 
 
 One of our neighbors, a famous breeder of Barred 
 Rocks, has for years claimed that the only sure way to 
 prevent white diarrhea in chicks is to feed them a liberal 
 supply of maggots. He has been a steady customer for 
 the rotten eggs from our hatchery. He exposes them 
 to the flies for a day and then lightly buries them. Shortly 
 there is as big a lot of wrigglers as any old hen would 
 want. He feeds these maggots regularly, and certainly 
 raises magnificent birds on them. It is probably safest 
 to use maggots thus produced under ground, for if the 
 eggs were not buried, there might be ptomaines de- 
 veloped. 
 
 In everything the poultryman should remember that 
 he cannot far transgress nature with immunity. If 
 chicks are once well hatched, then look to your brooding 
 system. 
 
 36 
 
 Li, My 'II 
 
Successful 
 Incubation 
 
 By P. COOK 
 
 The WEIMAR PRESS, Los Angeles, Cal. 
 
LIBRARY OF CONGRESS 
 
 002 857 364 9