APPENDIX. 



Thefe circum fiances did not efcape M, Boiiguer's at- 

 tention, and his ingenuity fuggefted to him an improve- 

 ment of the common log, which would correal the errors 

 likely to arife from the moft material of thefe circum- 

 ftances: a defcription of this improvement he publifhedat 

 large in the Memoirs of the Academy of Sciences for the 

 year 1747 j it has fince been abridged in the edition of his 

 Navigation by De la Caille. It appears extraordinary that 

 this log fhould never have been made ufe of by others ; — 

 the great reputation of the author, as well as the very good 

 reafons he offers in favour of his improvement, were fuf- 

 ficient inducements to me to try the experiment. 



In the log which I made ufe of, 



The length of the cone was — 12 inches. 



The diameter of the bafe — 5-^. 



The weight of the cone — 25 ounces. 



The diagonal length of the diver — 14 inches. 



The length of each fide — 9|. 



The weight of the diver — — 26 i ounces. 



The length of line from the diver to the cone, 50 feet; 

 the log line 5 1 feet to a knot. 



Whether M. Bouguer's log will (as he expeded) correct 

 the errors arifing from currents in the common log, I had 

 no opportunity of difcovering in this voyage. 



The fecond error, which no log will corre(9:, cannot 

 be attended with any bad effedl, as it mufl make the 



reckoning, 



9^ 



