TO THE READER.  
COURTEOUS READER,  
IN my Youth-hood I was employed in Clerkship under, and received some Mathematical Knowledge from Mr. John Marr, one of the Clerks of the Kitchen to His Present MAJESTY, when PRINCE of WALES, the said Mr. Marr being very Eminent for his Mathematical Knowledge, some testimony whereof may be evinced, from those excellent Dial's, wherewith the Gardens of our Late SOVEREIGN were adorned.  
Our Intestine Miseries increasing, I lost that Employment, and went Seven Years to Sea, most part of it in an English Merchantman, become a Man of War in the Venetian Service against the Turks, in which having leisure, I applied part of my Studies to Mathematics and Merchants-Accompts, and upon my Return fell to the Practice thereof, and afterwards professed Writing, Merchants-Accompts, and some Parts of the Mathematics; and having drawn up some Books of Accounts, and divers lose Questions, for the Instruction of my Scholars, in the Years 1652 I committed them to the Press, under the Name of An Introduction to Merchants-Accompts; they were again Reprinted in the Year 1664/5, without alteration; and in 1666, the Fire consumed the greatest part of the Impression: The Stationer hath since often urged me to alter and enlarge the same for another Edition, presuming, that I that have been much and lately concerned in great and Public Accounts, and have studied and been employed in the Affairs of Public Trade and Plantations, might alter the same to good advantage, and perchance others may be of the same mind; but I concur not, finding that my said long Experience hath not at all advanced my Knowledge in good Methods of Accounts, though I confess I understand the nature and Intrigues of bad ones much better than I did. Whereupon I have consented, and advised the Stationer to Reprint the same with the Addition of two more Accounts than were formerly extant, and was the more willing to do it at this time for this Reason, namely:  
That I might take the opportunity of acquainting those who are, or may be concerned, That I spend part of my time in Stating Merchants-Accompts, Ship-Accompts, or any Controversal Intricate Accounts, (concerning which, as some have, so more may become Suits in Chancery or Equity, commenced or depending;) and in Computing of Interest, the Variation or Forbearance of Leases, Mortgages, and Annuities; and am to be heard of at Mr. Robert Horns the Stationer, at the South-Entrance of the Royal Exchange, for whom this Book was Printed.  
And now as to the ensuing Work, I have this to say, That when I first Composed it, I observed a want of such Questions, that might not tyre out the patience of the Reader or Student, there being none but Journals and Leidgers of other Authors in Print, seeming to some like a Labyrinth of a more than sufficient length, and the which, when traced through, might possibly leave the Reader unskilful in these shorter Questions; some whereof have had their rise from real Affairs, which have happened much of the same kind. And now if the Reader be still unexperienced, and desirous to reap some benefit thereby, let me advise him to write out the Journals of some of these Accounts, omitting the Relative Numbers in the Margin, of the which see Section the seventh following, and are not to be made till the Parcel is entirely Posted, which that he may be enabled to do, he may use the ensuing Directions; but if this be thought too laborious, he may prick and examine over the said Questions, the Account itself gives Instruction for Balancing, the Balance of each Account, being Entered out of the Leidger at the end of the Journal Parcels.  
Divers Accomptants have made the Business of Simple and Compound Interest, and Annuities, the Subject of their Discourses: And I think it not improper to tell the Reader, that in 1664 I published a Paper, consisting of a quarter of a Sheet, and fitted for a Letter-Case, Entitled, The Doctrine of Decimal Arithmetic, Simple Interest, etc. as also of Compound Interest, and Annuities, generally performed for any time of Payment or Rate of Interest, by help of any particular Table of the forbearance of One Pound Principal.  
The which having been censured by some that understood it not, I think it not amiss, a little better to inform them, That the Table therein used, is a Table of Compound Interest, at 6 per Centum per Annum, for some Days, as well as (it is usual) for some Years, the which to the said, or any other Ratio, may be raised by several Methods, without any Extractions of Roots, or Aid of Logarithms; yea any Logarithm in the Canon may be easily computed thereby, and the Converse; also any Number of Mean Proportionals found between two Extremes given.  
The which Table and Precepts, removing the necessity of using a large Table of Logarithms, or of those multitudes of Tables, fitted for the several kinds of Annuity Problems, at several Rates of Interest, and several Terms of Payment, having been of constant and singular use to myself, and believing it will be of no less to others, I intent (God willing) to Reprint, to be fitted as before, to be a Vade-mecum in a Letter-Case, though with a larger Table, (which will remove some Operations hitherto necessary, to supply the want thereof) and besides an Explication thereof apart, illustrated with variety of Examples: And hope also hereafter to have some time to alter, amend, and Reprint other Treatises of my own, as my Book of Quadrants and dialing, but most especially my Treatise of Navigation, Entitled, The Mariners Plain Scale new plained; the rather, in regard His present Majesty, to His Immortal Praise, hath been pleased to settle a Maintenance for Forty Hospital Boys, and for a Learned Lecturer to teach them Navigation; on the Advancement whereof, the Splendour of the Government, and the Trade and Safety of this Nation doth so much depend, that any that love their Country cannot but be zealous for, as particularly is,  
Thy Friend and Wellwisher, JOHN COLLINS.   

DIRECTIONS TO Post or Transport the JOURNAL into the LEIDGER.  
I. For the Words of Expression.  
1. WHere you have many Debtors and one Creditor, proceed in order as they come; but where you have one Debtor and many Creditors, it is best (in my opinion) to Post all the Creditors first, and the Debtor last; in regard, by this means, the Figures of Reference are first Entered into the Journal.  
2. Immediately after the word To, which is always used on the Debtor side, must follow the Name of that Account that is discharged; the word By is always used on the Creditor side, and after it follows the Name of the Account that is charged.  
3. All Accounts of Wares, Voyages, Commodities, aught to be Posted at large in all the Particulars, with a Column ruled in the middle therein, to express the Number, Weight, or Measure of the Commodity; by help whereof the Number and Quality of the Goods unsold may be known.  
4. Upon the Account of Wares, it is best to express the Weight and Price, and on the Buyer or Sellers Account the time and manner of payment, if room permit: And here Note, That it is unusual to use above one Line in a Parcel in the Leidger. And now though Wares or Commodities are Posted at large, yet there is no such necessity, that other Accounts be the like.  
II. For the Manner.  
5. Discover by the Alphabet where that Account stands in the Leidger you are to charge, or if the Account be not yet Entered, frame an Account in a spare room, Entering the Title in a fair Italian Hand, and in the Calendar the Folio where that Account stands; then in the outermost verge Enter the Year, and in the first ruled space the Page of the Journal where that Parcel stands, in the next the Month, afterwards the Day, than the Words of the Parcel, and in the next ruled Column the Page of the Leidger where that Parcel stands Creditor, or if many Creditors, before the Column Figures expressing where those Accounts stand, and finally the Sum so charged; thus is the Debtor Parcel Entered: The like in several Accounts for many Debtors, when you have but one Creditor.  
6. Turn to the Folio in the Leidger, where that Parcel is to be discharged or made Creditor, and there Entering as before the Year, Page of the Journal, Month, Day, Words of the Parcel, Page or Pages of the Leidger where Entered Debtor, and finally the Sum; thus is the Creditor Parcel entirely Entered: The like for many Creditor Parcels in several Accounts, when you have but one Debtor.  
7. Lastly, In the Journal draw a Line between the Terms Dr/ Cr, above the said Line Enter the Page of the Leidger where that or those Parcels stand charged or made Debtor, and under the Line the Page or Pages where the said Parcel or Parcels are discharged or made Creditor: Observing by the way, that every Parcel is charged and discharged for the same Sum, either in gross, or at length.