Wilhelmi Bedwelli rigonum Architectonicum: THE CARPENTARS' RULE, Explained, reform, and enlarged: That is, A Table serving for the more exact, and speedy measuring of Board, Glass, Stone, and such like, both Plains and Solids, by the Foot, than ever heretofore hath in this kind, been set out or taught by any: Invented, and first published in the year 1612, by Wilhelm Bedwell, Parson of S. Ethelburghs London.  

Of the use of the Trigon in measuring of Plains by the foot.  
TO measure by this Table, is, by two numbers known, to find the third unknown. Things here to be measured, are magnitudes. And magnitudes or bignesses, are quantities which have either one or more dimensions, to wit, length, breadth, or thickness. These dimensions are here represented by numbers. Of the two numbers assigned, the one must be sought amongst those on the out side of the Trigon: The other amongst those underneath the base of the same. The numbers, as you see, do stand against the spaces enclosed between two parallel lines. Having found your numbers given, let your eye direct you through the opposite spaces against which they stand, from the one ascending; from the other sidewaies, or contrarily, until you observe both the spaces to meet, or fall into one. The number there found, is the dimension sought. Plains are magnitudes long and broad: Or, Surfaces are magnitudes of two dimensions, namely, length and breadth. Here the two numbers given, are that of the breadth, and the number of 12; 1 A Board of 18 inches broad, and 24 foot long, is to be measured. Here the breadth 18 taken amongst those under the base, and 12 amongst those on the side, do in the quadrate where their spaces meet, give 8 inches for the length desired. Now because 8 inches is contained in 84 foot 36 times▪ therefore the board given, doth contain 36 foot of plain measure. 2 A pane of Glass is 8 inches broad. Here 8 taken amongst those on the side; and 12 underneath the base, do set us out 18 inches for the length. If the breadth be greater than 24, that is, than any number enclosing the Trigon, then take the half, one third part, one quarter, etc. and the number found shall be two, three, or four foot, &c of plain measure. 3 A Table of one yard and a quarter (or 45 inches) broad is to be measured. Here 45 inches is greater than any number about the Trigon; therefore I take 15 the third part of the breadth, and 15 and 12 I find to point to 9 and 3/5 for the length desired. Therefore I aver, that every 9 inches, and 3/5 parts of an inch in length of that table, shall contain 3 foot of plain measure. 4 A room of 16 foot broad, and 48 foot long is to be floored; I would know how many foot of Board it will ask to cover it. Here 16 foot, that is, 196 inches is greater than any about the Trigon; therefore I take 16 the 12 part thereof: and 16 and 12 do allow 9 inches for the length. Now because 9 inches are contained in 48 foot 64 times; and 64 times 12 are 768. Therefore I say, the floor will require 768 foot of board to cover it.   

The use of the Trigon in the measuring of Solids by the fo●●.  
SOlids or bodies have three dimensions, to wit, length, breadth, and thick●●●e. And of these commonly the breadth and thickness are given; the length is so●● 1 A square timber stick of 12 inches broad, and 12 inches thick, is to be measured. Here 12 and 12 do point out 12 inches for the length desired. 2 ●●one is 18 inches broad, and 16 thick. Here I find 6 inches for the length ●●ght. If either one or both of numbers given, be greater than any about the Trigon, ta●●s afore, either the one half, one third, and the number found shall answer in a pr●●tion, as afore. 3 Suppose a stone were 4 foot (or 48 inches) over, and 8 in●● thick. Here 24 the half of 48, and 8, do assign 9 inches for the leng●● desired. Therefore say, that every 9 inches in length of that stone, shall ●●eine 2 foot of solid measure. 4 Admit the stone were a yard square, that is, 〈◊〉 inches broad, and 36 inches thick. Here both the dimensions, to wit, be●●●readth and thickness, are greater than any of those about the Trigon. ●●●●efore I take 18 and 18, the half of each; and I find them to meet in the 〈◊〉 where you have 5 inches and 1/3. Therefore I say, that every 5 inches, and 〈◊〉 of an inch doth contain 4 foot of stone.  
To measure by that our ruler, being by the crossing of two lines given, to find out the third; And the eye not able in many cases precisely to discern at what parts of an inch that crossing is; some have desired that these several meetings might be noted on the verge of the ruler, either above or beneath; but th● being not to be done without confusion, I do advise them to have recourse to this our Table, where they shall receive satisfaction: And withal it shall teach them how to do it. Other uses of this our Trigon, shall, God willing, shortly be declared: for this straightness of room will admit of no long discourse. Vale.   

24  23 3 24 22 3 141/129 3 1/25 25 21 3 68/121 3 108/253 3 8/11 22 20 3 45/49 3 57/77 3 ●●/161 3 ●/7 21 19 4 8/25 4 4/35 3 51/55 3 87/125 3 3/5 20 18 4 284/361 4 57/95 4 44/●33 4 28/209 3 417/437 3 15/19 19 17 5 ⅓ 5 1/19 4 ⅘ 4 4/7 4 4/11 4 4/23 4 18 16 5 283/●89 5 11/17 5 115/323 5 7/85 5 100/119 4 116/181 4 164/391 4 4/17 17 15 6 ¾ 6 6/17 6 5 27/38 5 2/5 5 1/7 4 10/11 4 16/23 4 1/● 16 14 7 17/35 7 1/5 6 66/85 6 2/5 6 6/95 5 19/25 5 41/105 5 13/55 5 1/77● 4 4/● 15 13 8 40/49 8 18/35 7 5/7 7 31/119 6 6/7 6 66/133 6 6/35 5 43/49 5 47/77 5 59/161 5 1/7 14 12 10 38/169 9 45/91 8 168/195 8 4/13 7 181/28● 7 5/13 6 246/247 6 42/65 6 30/91 6 6/743 5 233/299 5 7/●● 13 11 12 11 1/13 10 2/7 9 3/5 9 8 8/17 8 7 33/57 7 1/5 6 6/7 6 6/11 6 6/23 6 12 10 14 34/121 13 1/11 12 12/143 11 17/27 10 16/55 9 2/11 9 45/187 8 8/18 8 56/209 7 47/55 7 111/131 7 17/121 6 210/253 6 6/1● 11 9 17 7/25 15 39/55 14 3/5 13 19/65 12 12/35 11 13/25 10 ⅘ 10 14/85 9 1/5 9 ●/95 8 16/25 8 8/35 7 47/5● 7 59/125 7 1/5 10 8 ●● 19 1/5 17 5/11 16 14 10/13 13 5/7 82 ⅘ 12 11 5/17 10 ⅔ 10 2/19 9 3/5 9 ●/7 8 ●/2● 8 ●/2● 8 9 7 27 ●● 21 8/5 19 7/15 18 16 8/13 15 3/7 14 ●/5 13 ½ 12 12/13 12 11 7/19 10 ⅘ 10 2/7 9 9/11 9 9/12 9 8 6 35 11/49 30 6/7 ●● 24 24/35 22 34/77 20 4/7 18 90/91 17 ●1/49 16 16/●5 15 5/7 14 6●/129 13 1/7 12 132/133 12 12/35 11 111/147 11 27/77 10 ●●/161 10 ●/7 7 5 48 41 1/7 36 ●● 28 ⅘ 26 ●/11 24 22 2/1● 20 4/7 19 ●● 18 16 16/17 16 15 9/17 14 2/5 13 5/7 13 ●/11 12 12/23 12 6 4 69 3/25 57 3/5 49 13/35 43 1/5 3●● 34 14/25 31 23/55 28 ⅘ 26 3●/65 24 24/35 23 ½5 21 3/5 20 28/●5 19 1/5 18 18/95 17 7/15 16 16/35 15 19/●5 14 18/115 14 1/5 5 3 108 86 2/5 72 61 5/7 54 ●● 43 1/5 39 3/11 36 33 3/13 30 6/7 28 ⅘ 27 25 7/17 24 22 14/19 21 3/5 ●0 4/7 19 7/11 18 18/2● 18 4 2 192 144 115 1/5 96 82 ●/7 72 ●● 57 3/5 52 4/11 48 44 4/13 41 1/7 38 2/5 36 33 15/17 32 30 6/19 28 ⅘ 27 8/7 26 ●/1● 25 ½● 24 3 1 432 288 216 172 ⅘ 144 123 3/7 108 ●● 86 ●/● 78 6/11 72 66 6/13 68 5/9 57 3/5 54 50 14/17 48 45 9/19 43 1/5 41 1/● 39 3/11 37 1●/2● 36 2 1728 864 576 432 345 3/5 288 246 6/7 216 ●92 172 ⅘ 157 ●/●● 144 132 12/23 123 3/● 115 1/5 108 101 ●●/17 96 90 18/19 86 2/5 82 2/7 78 6/11 75 3/23 72 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24