APPENDIX. 
XXV 
Pisania then, is placed in longitude 13 0 28', according to thfo result; 
and in latitude 13 0 35' north, according to Mr. Park's observation, by 
sextant. 
The causes of the apparent wanderings of Mr. Park having been ex- 
plained in the former part of this work, it will be no farther necessary to 
trace his course, than merely to explain the connection of the different parts 
of the data for the general construction. 
Since the scale of the Map is fixed by the computed distances arising on 
the intervals of time employed in Mr. Park's route, it is possible that some 
readers may be startled at the idea of following such an apparently vague 
authority. Those, however, who have been much in the habit of observ- 
ing their rate of travelling, will be easily convinced that distances may be 
approximated ; and those in particular who have been much accustomed to 
travel in countries, where time regulates the distance ; or who have been in 
habits of working up geographical materials of this kind, will be the most 
easily convinced. It will of course be understood, that calculations of this 
kind can only be received from persons of judgment and experience: and 
also, that when opportunities of checking them, occur, they are always re- 
sorted to ; after which, of course, no alternative remains, but to adopt the 
corrected distance. 
In the present case, the rate of travelling of camels* does not apply ; 
as Mr. Park's journey outwards was made on horseback, and his return 
chiefly on foot. Nor are camels, indeed, in use in that line of route. 
The checks to be employed, are the number of journies reported by the 
travelling merchants, from different points of Mr. Park's route to Sego 
and Tombuctoo ; and also those from the quarters of Morocco, Tunis, 
and Fezzan, to Tombuctoo ; using as a scale, the rate arising on the 
route between Fezzan and Egypt, Morocco and Jarra, as the best known 
lines of distance. These, altogether, furnish such kind of authority as will, 
I trust, lead to a satisfactory conclusion; as the general coincidence is cer- 
tainly very striking. 
My mode of procedure, has been, to calculate, in the first instance, 
• See Phil. Trans, for 1791. 
d 
