ON THE KEW OBSERVATORY. 179 
to A, and C is the clock-case. d! is the long pendulum within C, and d? its 
very heavy bob. εἶϑ is a lever which enters C through a slit, and whose ful- 
erum is at d*: a spring (not shown) forces the nearest end of d° upwards 
when it is not stopped in the horizontal position. εἶδ is a little stop fixed 
upon d3. d® is a rod attached, by a pivot, through a slit to 8, and passing 
through a hole in a piece of wood (not shown) attached to A. This part of 
the instrument is so constructed, that when the clock is not in motion αἴ is in 
a higher position than that shown, and the extremity of the then inclined pen- 
‘dulum αἱ is placed by the observer against its nearest side, preventing vibra- 
tion; but when it is to be set in motion, d° is brought into the position shown 
by depressing the handle at the top of ἀδ. d7 is a gut-line proceeding from 
the barrel of the clock contained in C, passing over B, round a pulley at an 
angle of A, and sustaining a weight, d’, which gives motion to the clock-work. 
d® is another line sustaining the winding-up weight, d!°, which line passes 
round another pulley (unseen) under B, and entering C is attached to and 
winds round the barrel of the clock in the contrary direction to d?. 
The continuity of d7 is interrupted by a small steel wire, upon which turns, 
or hangs freely, a little pointed brass plate d'4, pressing very lightly on B. 
When the clock is at rest d' is adjusted to the upper part of a “ Hrequency 
Paper” fixed (by drawing pins) upon B, and the whole is ready for use. 
When an observation is to be commenced, the time (by our chronometer) is 
written exactly opposite to the point of the index d'* (which has been placed at 
the top of the paper by pulling down the weight d'°); the conductor is then 
discharged, and the pendulum started (by pressing downd® )at the same moment. 
As the charge of the conductor advances towards iis former intensity (or 
any other approximative maximum intensity), marks are made opposite to the 
index from time to time at convenient intervals ; and the various tensions are 
noted down at those intervals near the marks until a maximum has been 
arrived at by estimation (7. e. when no increase of tension seems to be going 
on, or when a decrease has actually begun). The observation now ceases, 
and the fiducial edge of a scale, accurately divided into spaces corresponding 
with the rate of our chronometer, is applied to the above-mentioned first and 
last marks or “notes of tension,” and occasionally to other of the marks. Or, in 
order to estimate as accurately as possible by these means the time of a maxi- 
mum, the observation is carried on even beyond the apparent first maximum. 
i A copy of one of the “Frequency Papers” is annexed which has been 
employed for procuring the “ Frequency Observation of Atmospheric Elec- 
tricity,” where it may be seen that on May 12th, 17" 17', the charge of the 
conductor was positive and =65 divisions of the Electrometer, and that the 
Frequency (at about 11 minutes afterwards) was =11!' 15" (the charge had 
increased to 67°5 divisions). 
The remaining apparatus and instruments of various kinds belonging to 
the Association, or on loan to it, do not seem to require particular notice 
here. They are carefully preserved. 
If. OBSERVATIONS. e 
The only observations (or experiments) worth notice here, on the fre- 
_ quency of atmospheric electricity which have been made at Kew this year 
(by means of apparatus particularly described in the Society’s Reports for 
_ 1843-44.), commenced on the 12th of May and terminated on the Ist of 
June. The plan of procedure adopted was intended as merely preliminary, 
and in order to arrive at certain data for choosing the preferable mode of 
instituting a regular series of such observations (selt-registering or ordinary ). 
_ The instructions given to the observer were as follow :— 
_© The pillar lamp, and the lamp of the lantern belonging to the electrical 
