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XXIV. Hourly Observations on the Barometer ; with experimental investiga- 
tions into the phenomena of its periodical oscillation. By James Hudson, 
Assistant Secretary and Librarian to the Royal Society. Communicated 
by John William Lubbock, Esq. M.A. Vice President and Treasurer. 
Read June 21, 1832. 
When Mr. Lubbock undertook, last year, an examination of the Meteoro- 
logical Observations made daily at the Royal Society, during the preceding 
four years, he found that no satisfactory result connected with the diurnal 
variation of the barometer could be obtained from them, in consequence of the 
stated hours of observation not recurring after sufficiently small intervals of 
time. From the interesting nature of the phenomena of the barometer, and 
from the circumstance of no observations for determining the amount and 
peculiarities of its horary oscillation having been made at the Royal Society, 
I proposed to undertake as extensive a series of hourly observations on this 
instrument as my official duties and the state of my health would permit ; — 
to prosecute such experimental investigations into collateral branches of the 
inquiry, as the anomalies presenting themselves might require ; — and to insti- 
tute, finally, a comparison between my own results and those derived from the 
labours of other observers, both in this country and on the Continent. 
In endeavouring to accomplish these objects, I have been anxious in the 
first instance to present to the Society a series of observations, made at 
equal intervals of time, — -in sufficient number, — through an extended pe- 
riod, — and with instruments, whose peculiarities of excellence or defect are 
well known and understood ; and which, being conducted with every care, 
may furnish preliminary data for explaining the anomalies of its hourly and 
daily oscillation ; determining, if possible, the laws which regulate its perio- 
dical changes ; and ascertaining the circumstances which accelerate or retard 
the operation of these laws : being guided, in the progress of the inquiries, 
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