[ ^3S ] 



this purpofe, before the pointers are turned to any fet of figures, 

 the pointer that reprefents thoufands is turned to the clafs that 

 is wanted ; as foon as the correfpondent anfwers this fignal 

 Thousands is returned to O, and inftantly all the pointers are 

 moved to the places which denote the figures required for any 

 word or fentence. 



When the clafs is thus afcertained, an index, which Aides on 

 the mahogany cover of the book, is fet to the column belong- 

 ing to this clafs ; the number of thoufands is then opened by 

 the ruler as foon as it is read off by the telefcope. The num- 

 ber of hundreds is opened by the pages where they are cut 

 away and the number of tens and units is feen on the page. 

 As the pointers are moved in fucceffion from thoufands to 

 units the different divifions of the book can be opened as faft 

 as the pointers are moved. The order of this book might be 

 reverfed with apparent advantage, by dividing the book into 

 claffes by the mahogany rulers, &c. but I prefer, for reafons 

 which it would be tedious to infill upon, the arrangement which 

 I have followed. 



As fecrecy is an objedl of the greateft confequence, I fhall 

 endeavour to point out, in a few words, the fuperiority of thi. 

 mode of communication over any alphabetical arrangement, 

 not only in point of expedition but of concealment. 



Although 



