, j 2 Mr. Rennell on the Rate of 
although Mr. Carmichael failed in the attempt to afcertain his 
road diftance by this method, yet his procefshas furnifhed others 
with the means of ascertaining the whole diftance in the aggre- 
gate, andof proportioning the parts throughout. For, as the diredt 
diftance is given by the celeftial obfervations, and a complete 
traverfe table by the journal, the data are perfedt. And when 
the reader is informed that Mr. Carmichael’s whole line of 
bearing, by compafs , between Aleppo and Bufforah, nearly 720 
J3riti(h miles, coincided with the bearing line given by the 
celeftial obfervations ; by which it appears that the error could 
amount only to the mean quantity of the variation throughout, 
which might have been from fix to feven degrees at that time 
(1751); he will give Mr. Carmichael credit for much 
general accuracy. And it is not improbable, that even a consi- 
derable portion of the above error may have arifen from the 
im perfection of his inftrument *. 
The fecond journal was kept by Colonel Capper, in 177^’ 
and was publiftied feveral years ago ; and the third, which 
contains little more than the time in detail, was communicated 
by my friend Mr. Hunter, who crofted the defert in 1767. 
The time given between Aleppo and Bufforah, by thefe 
journals refpedtively, is as follows : 
By Mr. Carmichael . 322 hours. 
Colonel Capper . 310 
Mr. Hunter . 299! 
* I find, by Mr. Drummond’s chart of the road between Aleppo and Antioch 
(1747), that the variation was then about 6 degrees wefterly. This is proved by 
comparing his magnetic bearing line between thofe places, with that given by the 
difference of latitude In the head of the Gulf of Perfia, the variation was 
7 degrees in 1785. 
But 
