IN CENTRAL AFRICA. 293 
seconljr, by attending to the declination of the compass. 
These lines were at first formed without any other modi- 
fication than the necessary substitution of the true north 
for the magnetic north^ in the night journeys. The di- 
rection of the first line from Fez gave me a very fair 
position for Timbuctoo ; and that of the second line from 
Time furnished me with another but little different^ and 
which the situation of the parallel of Sego brought con- 
siderably nearer to the first : whatever uncertainty still 
remained has been cleared up by new data^ of which it 
would have been difficult not to have made some use. 
Whilst at Time, the idea struck M. Caiilie of ob- 
serving the length of the shadow of a style at midday ; 
his long stay there gave him an opportunity of making 
the observation twice : the first time, which was on the 
30th of October 1827, the height of the style, with every 
reduction, was 0, 706 metre \ that of the meridian shadow 
was equal to 0, 2945 metre.* The second observation 
was made on the J st of November 1837 5 but this mea- 
surement cannot have been taken with so much preci- 
sion. It was the shadow, properly speaking, which was 
* The lengths of the style and of the shadow were taken with 
cords, which have been brought back to France, and which I have 
measured with the utmost possible care, comparing them with a good 
copper metre. 
The style was a very straight stick, placed quite vertically, by 
means of a plummet, which the traveller brought away with him, 
and which is deposited at the vice- consulate at Tangier, in the hands 
of M. Delaporte. 
