80 F REPORT—1862. 
extent, and reasons were adduced, in the absence of data for calculating the exact 
height, for concluding that it does not extend to the moon. It was argued on the 
hypothesis of the atomic constitution of bodies, that the upward resultant of the 
molecular forces on any atom, since it decreases as the height increases, must 
eventually become just equal to the force of gravity, and that beyond the height at 
which this equality is satisfied, there can be no more atoms, the atmosphere termi- 
nating with a small finite density. It has been generally supposed that the earth’s 
atmosphere is about 70 miles high, but on no definite grounds, and the estimates of 
the height have been very various. Against the opinion that it extends as far as 
the moon, it was argued that, as the moon would in that case attach to itself a con- 
siderable portion by its gravitation, which would necessarily have some connexion 
with the rest, there would be a continual drag on the portion more immediately 
surrounding the earth, and intermediately on the earth itself, which would in some 
degree retard the rotation on its axis. Hence if, as there is reason to suppose, the 
rotation be strictly uniform, the earth’s atmosphere cannot extend to the moon. The 
author also stated that if by balloon ascents the barometer and thermometer were 
observed at two heights ascertained by observation, one considerably above the 
other, and both above the region in which the currents from the equator influence 
the temperature, data would be furnished by which an approximate determination 
of the height of the atmosphere might be attempted. 
On the “ Boussole Burnier,”’ a new French Pocket Instrument for measuring 
Vertical and Horizontal Angles. By F. Gatton, F.R.S., F.R.G.S. 
This instrument is about 3 inches long and ¢ inch deep. Its outside is composed 
of two faces of brass with pear-shaped outlines, separated by vertical sides. In 
the body of the instrument are two delicate circles placed in parallel planes; at 
its smaller end is a cylindrical lens, which views the nearer graduations on the 
rims of the two circles; on the upper face of the instrument are sight-vanes like 
those of an azimuth compass; on the lower face is a light universal joint, which is 
used when the instrument is attached to a support, and not held, as it may be, in 
the hand. 
One of the circles is of aluminium, and is borne by a compass-needle; it gives 
horizontal angles when the instrument is held horizontally. The other is of silvered 
copper, unequally weighted, and is supported by a delicate axis playing in jewelled 
holes: it gives vertical circles through the action of gravity when the instrument 
is held vertically, just as the compass-circle gives azimuthal angles through the 
action of the magnetic force when the instrument is held horizontally. 
The remarkable simplicity and compactness of the Boussole Burnier would make 
it useful to the traveller, the geologist, and the military engineer. It is the inven- 
tion of Lieut.-Col. Burnier of the French Engineers, and has been perfected in its 
details by M. Balbreck, No. 81 Boulevard Mt. Parnasse, Paris. 
European Weather-Charts for December 1861. By F, Gatton, 7.B.S., F.R.GS. 
The author submitted for examination a series of printed and stereotyped charts, 
compiled by himself, that contained the usual meteorological observations made at 
eighty stations in Europe, on the morning, afternoon, and evening of each day of 
December 1861. They were printed partly in symbols and partly in figures, in such 
a form that each separate group of observations occupies a small label, whose centre 
coincides with the geographical position of the station where the observations were 
made. The amount of cloud is expressed by shaded types, the direction of the wind 
by an equivalent to an arrow, and its force by a symbolical mark. The tempera- 
ture of the wet and dry thermometers, and the barometric readings (reduced to zero 
and sea-level) are given in figures. As the charts had been too recently printed to 
admit of a thorough examination, and as they were ultimately to appear as a sepa- 
rate publication, the author abstained from other deductions than those that were 
obvious on inspection. Among these, the enormous range and the simultaneity of 
the wind-changes, testifying to the remarkable mobility of the air, were exceedingly 
conspicuous. 
