3 1 6 On the Invention of the Telegraph. 



(hall be put into practice, thofe, and many more than I can 

 think of at prefent, will of themfelves occur ; fo that I do 

 not in the leaft doubt, but that with a little practice, all 

 things may be made fo convenient, that the fame character 

 may be ften at Paris within a minute after it hath been ex- 

 pofed at London ; and that the characters may be expofed 

 fo quick after one another, that a conipofer fhall not much 

 exceed the expofer in fwiftnefs; and this not only at the 

 diftance of one ftation, but of a hundred ; for, fuppofing all 

 things ready at all thofe feveral Rations for obferving and 

 expoliiig, as faft as the fecond obferver doth read the charac- 

 ters of the firft expofer, the fecond expofer will difplay them 

 to the obferver of the third ftation, whofe expofer will like- 

 wife difplay them for the fourth obferver, as fait as his ob- 

 ferver doth name them to him, or write them down. 



" There maybe many objections brought againft this way 

 of communication, becaufe it has not yet been put in prac- 

 tice •, but hardly any that may not be eafily anfwered and 

 obviated." Dr. Hook illuftrates his invention thus : 



" Let ABC (Plate X. fig. 4.) reprefent three very long 

 mafts or poles erected ; E, the top-piece, that joins them 

 all together ; D, a fcreen, behind which all the deal-board 

 characters hang upon certain rods or lines, and may, by the 

 help of fmall fines connected with each of them, be ex- 

 pofed at F, or drawn back again behind D, as occafion fhall 

 require." 



XVII. Propofttions refpecling the Mechanical Power of the 

 Wedge, by Mr. Peter Nicholson of Newman-JIreet. Com- 

 municated by the Author. 



VV RITERS on mechanics, in treating of the wedge, have 

 frequently drawn falfe conclufions refpecting the proportion 

 which exifts between the impelling power applied to the 

 head, and the refilling powers oppofed to the fides 5 and 



thofe 



