18 ‘ REPORT—1846. 
Association at Cambridge, to bestow some attention to the subject, and was enabled 
to report to the meeting that he had succeeded in devising a method of continuous 
registration with as much accuracy as the purposes of science require. 
Various mechanical means have been proposed for the registration of all meteoro- 
logical instruments except the magnetometers ; but the amount of magnetic force is 
so small, that the variations of its intensity and direction are incapable of actuating 
any mechanism, and therefore can only be expected to be recorded by the aid of 
photography ; and by these means the proposed object had been accomplished: as 
however a detailed description of the apparatus by which magnetic variations have 
been registered is already in the hands of the Royal Society, Mr. Brooke did not con- 
sider himself authorized to enter into a description of it, further than is necessary to 
explain those modifications of the apparatus which formed the subject of the present 
communication. A piece of prepared photographic paper is placed between two con- 
centric cylindrical glass surfaces, which are carried round their common axis, placed 
horizontally, by the hour-hand of a time-piece movement. The paper consequently 
passes vertically behind a horizontal slit in a case of suitable form in which the 
cylinders are enclosed to protect the prepared paper from the influence of diffused 
light. A cylindrical refractor, the axes of whose surfaces are parallel to the slit, is 
placed in front of the slit, and at such a distance from it that the rays of light falling 
on it may be refracted to a focus on the paper. In the case of the magnet, a sphe- 
rical concave reflector is attached to a stem by which the magnet is suspended, and a 
camphine lamp having a vertical narrow slit in the chimney is placed at such a dis- 
tance from it that an image of the slit may be formed at the distance of the paper ; 
a portion of the image is condensed vertically by the cylindrical refractor, and im- 
presses the photographic paper. Some registers obtained by this apparatus were 
exhibited to the Section, from which the position of the declination magnet might be 
determined by a scale with a probable error not exceeding 10", and in some, not ex- 
ceeding 5". 
In obtaining the register of the barometer, a lamp is placed in front of the appa- 
ratus, and a screen with a narrow vertical slit attached to the end of the long vertical 
arm of a lever is interposed between the refractor and the horizontal slit before de- 
scribed. This lever is balanced, anda short horizontal arm rests on a float supported 
by the mercury in the shorter tube of a siphon barometer; the lengths of the arms of 
the lever having been taken as 10 to 1, the variation of the height of the column will 
be magnified 5 times, and the light passing through the point at which the two slits 
cross, will trace out a line sufficiently distinct to indicate the height of the barometer 
at any period to the =4,th of an inch. 
The registration of the thermometer and psychrometer was obtained by interposing 
the stem of these instruments with a flat bore, wide enough to exclude the light, be- 
tween the slit and the refractor ; as however this expedient is not new, it need not be 
more particularly described; the only novelty in Mr. Brooke’s apparatus was in 
placing the stems of the two instruments on opposite sides of the cylinder, so as to 
obtain a register of both on the same paper, and in making the bulbs long narrow 
cylinders instead of spheres, in order to increase the surface and consequently the sus- 
ceptibility of changes of temperature. By having each degree about 3th of an inch 
long, the temperatures may be obtained at any time to jth or oth of a degree. 
Table of the Fall of Rain in the Lake Districts of Cumberland and West- 
moreland, &e. in the Year 1845. By J. F. M1Luer. 
The writer exhibited a series of registers in a tabular form, from which it resulted 
that at Seathwaite there have been 31 days in which the fall was between 1 and 2 
inches, five days between 3 and 4 inches, one day between 4 and 5 inches, and one 
day between 6 and 7 inches. ; 
On the 27th of November, 1845, there was measured at Seathwaite 6:62 inches, 
and on the 26th and 27th nearly 10 inches, being the greatest quantity of rain which 
has ever been measured in the same period in Great Britain. At Langdale Head in 
Westmoreland, the fall on the 27th was 6:28 inches, and on the 26th and 27th nearly 
9 inches. 
