— 
History of Astronomy for the Year 1805. 349 
mense quantity of meteorological observations in Piedmont, 
and who still continues them, notwithstanding his great age, 
has sent us those of 1805. 
Meteorology and.navigation may equally claim a memoir 
by M. Biot,: which,explains, by means of an interior mag- 
net, all the declinations and inclinations of the needle, obs. 
served by M. Humboldt in his travels. : ee 
There is an unpublished memoir of Tobias Mayer, of 
which his son had the goodness to send me an extract. It 
contains an hypothesis by which ‘he explains the observed 
inclinations and declinations. He supposes a very small 
magnet in the interior of the earth having two poles, the 
centre of which magnet is removed from the earth by one- 
seventh of the radius, and recedes from it each year one 
thousandth part. : 
The line drawn: from the centre of the earth through that 
‘of the magnet was in 1750 at 201° of longitude and 17° of 
north latitude: the longitude increases 9’ a year, and the la- 
fitude 14’. . 
The axis perpendicular to the Ime joining the centres, 
drawn in such a manner’ that the plane which passes by 
this axis and this line, is inclined to the meridian of this 
line 114 degrees towards the east on the north side; and 
this angle increases 8} minutes a year. 
M. Azuni has published a dissertation upon the origin of 
the compass, in order to prove that the French were the first 
who used it: it was known iu France in the 12th century, 
by the name of mariniere : it was used in the reign of Saint 
Louis. Gioia d’Amflai, to whom it has been attributed, 
did not live till about the year 1300. The figure of the 
fleur de lys has been used in the compasses of all nations. 
I have already remarked, in my Abridgment of Navigation, 
that father Ximenes, the celebrated Italian astronomer, has 
proved the priority of the French in his work Del Gnomone 
Fiorentino, p. 59. 
Mr. Earnshaw and Mr. Arnold, two English watch - 
makers, on the 7th of June 1804 presented to the Board 
of Longitude of London their escapements for time-keepers 
or 
