to numbers, beginning with unity and proceeding in regular 

 order to the extent required, which 'tis fuppofed will not exceed 

 ten thoufand. Then if the line in which the fignals are to be 

 placed be 25J: yards 7 inches Iqng, it may by divided into one 

 hundred parts of 7 feet 8 inches each, the extremities of which., 

 parts fliould be numbered, and if there be two lights or two 

 flags diftinguifliable by their fliape, or by their colour, or by both, 

 one may reprefent units, and the other hundreds, by which any 

 number under ten thoufand, and of courfe any word or fentence 

 in the vocabulary can be exprefled : for inftance, if the number 

 of the word to be communicated be 5796, the flag or light 

 which reprefents hundreds is to be placed in the graduation of 

 the line of fignals marked 57, which fignifics fifty-feven hundred, 

 and the fignal which reprefents units is to be placed in the gra- 

 duation marked 96, which denotes the number ninety-fix, the 

 fum of which is the fymbpJical number propofed. 



In order to obferve thefe fignals and their places, Mr. Cavallo's" 

 inftruraent (defcrlbed in the Philofophical Tranfadions of the 

 year 1791) feems to be w^jl adapted.; it is a micrometer of a 

 very fiaaple kind, applied to a three feet achromatictelefcope, 

 which magnifies abou.t eighty-four times, and with which he 

 coitld meafure an angle of 7 feconds accurately ; the fcale of 

 it may be fo marked that the numbers reprefented by the fignals 

 may be feen at the time of obfervation without calculation or 

 moving any of its parts. 



L 2 Mr. 



