390 THE CENTURY, 



surface of each plate, are to have a groove cut in each, 

 similar to a screw head ; this is to be effected by cutting 

 lines from end to end of the plate, as shown at e e, e e, 

 Fig. 1. With a graver a small dot is next to be made, 

 all to the right on one plate, and all to the left on the 

 other ; or, vice versa, of each line occupying the small 

 circular end of each roller. It is now evident that, by 

 using a small chisel-shaped steel instrument, or key, 

 with which to turn the roller, the small dotted line on 

 its end, may be so varied as to form any alphabetical 

 arrangement. 



The position of the dotted line admits of sufficient 

 variety to take in 24 letters, distinct enough to the 

 eye, without increasing the size of the seal. In this 

 alphabet only three variations are supposed to be made 

 from the horizontal and perpendicular, one very slight 

 on either side, the other greater, and the third at an 

 angle of 45. It only requires a transposition of the 

 letters to produce a correspondence which shall be 

 private between two persons. The use of two faces 

 to the seal is obvious, one serving to compose on, and 

 the other, being a reverse, to make an impression on the 

 wax. Were this not the case, a sentence would have 

 to be written from right to left. Its use might be mul 

 tiplied by making each cipher refer to an entire word 

 or sentence; as, if a, stood for men&quot;; , for horses; 

 c, food; d, money; and so forth: a mode which it 

 would be next to impossible for any third party to 

 decipher. See Mechanics Mag. vol. x. 



2. 



How ten thoufand Perfons may 

 ufe thefe feals to all and every of 

 the purpofes aforefaid, and yet keep 



