42 PHILOSOPHICAL TRANSACTIONS. [aNNO 17Q1. 



ther igSi hours between Aleppo and Bagdad. The direct distance between 

 those places is 393 geographic miles ; and by the route traced by Mr. Irwin, the 

 road distance comes out about 4144, or British miles 480. And this number, 

 divided by IQS^-, gives 2.48 per hour for the camel's rate; or within a very 

 small fraction of Mr. Carmichael's rate, his being, as we have just seen, 2.475 ; 

 and the mean of the two 2.-1 78. And here it may not be amiss to add to these, 

 the result of Mr. Holford's ; as well as the estimates of the camel's rate, formed 

 by 7 different persons. All these are placed in one point of view, in the follow- 

 ing table. 



Mean of the 7 estimates 2.35 ; mean of the 5 experiments 2.51 ; mean of 

 Carmichael's and Irwin's 2.478. So that, all circumstances taken into the case 

 (and particularly this remarkable one, that of 3 persons who attempted to ascer- 

 tain the rate, by counting and measuring the camel's foot-steps, none reckoned 

 it higher than 2-i-, and one went so low as 2^,) Mr. R. thinks the rate of 2-^ 

 miles per hour may be used, as differing but a shade from the general result ; 

 and as having the most manageable fraction. 



Thus it appears that the hourly rate of the camel may be applied as a very 

 useful scale to the African geography ; whenever the use of watches shall be 

 adopted by the native travellers employed by the African Association ; and with 

 still greater advantage, of course, if Europeans are employed. And if Mr. 

 Carmichael could describe the general bearing, on a line of more than 700 Bri- 

 tish miles, so nearly as within 6 or 7° of the truth ; and that with a pocket 

 compass ; nothing more need be said concerning the advantages that may be de- 

 rived from the use of that valuable instrument, aided by such a scale as has been 

 described. Mr. R. considers only the progress of the light and heavy caravans, 

 in which the camels are left to pursue their journey quietly and at leisure ; and 

 with the regularity of a machine : and not that of the light camels, which are 

 not only freed from incumbrance, but are also urged on. 



There are 2 examples of the heavy kind, and 3 of the light kind, where the 

 time has been regularly kept : besides a 3d example of the heavy kind, where 

 the necessary regularity is wanting, but yet containing evidence sufficiently strong 

 to corroborate the other two. The heavy caravans were those of Mr. Carmi- 

 chael and Mr. Holford; the first of 1000 camels, of which 600 were loaded, 

 went, on a journey of 45 days, at a mean each day 7'' 10"'. The 2d, with 50 

 loaded camels, on a journey of 15 days, at 7*^ 40'" each day; the mean of the 

 two is 7^ 25"". The 3d, Teixeira, with 130 loaded camels, on a journey of 21 

 days, about;'' 30'" a day. The mean of all, per day, 7'' 27"". 



