398 
Scientific Intelligence. 
1818, - 
- - 48.83 Inches* 
1819, - 
31.12 
1820, - 
43,5 
1821, - 
52.6 
1822, 
39.3 
Average of Five Years, 
43.07 
Prof. Silliman’s Journal , vol. iv. p. 327. 
20. On the Periodical reappearance of Thunder-Storms .« — 
That celebrated philosopher Count Volta remarked the extra- 
ordinary tendency which thunder-storms have to reappear many 
days successively about the same hour, and, what is still more 
remarkable, at the precise spot where they at first appeared. 
i( It is necessary,” says Volta, “ to inhabit a mountainous 
country, and particularly the neighbourhood of lakes, such as 
Como, the precincts of Lario, Verbano, Varese, Lugano, Lecco, 
and the whole mountains of Bianza, Bergama, &c. in order to 
be convinced of such periods and fixations (so to speak) of 
thunder-storms at this or that valley, or opening of a mountain, 
which last, until some wind or remarkable change in the atmo- 
sphere shall occur to destroy them.” Count Volta ascribed this 
very remarkable phenomenon to a modification in the ambient 
air produced by the thunder-storm of the preceding day. — 
Configliachi’s Giornale di Fisica , quoted by Mr Ronalds. 
21. Periodical Rise and Fall of the Barometer. — Colonel 
Wright, Member of the Ceylon Literary and Agricultural So- 
ciety, is said to have discovered, that within the Tropics the 
mercury rises and falls twice within 24 hours, with such regu- 
larity as to afford almost an opportunity of measuring the lapse 
of time by this instrument. — Ceylon Government Gazette. 
22. Influence of Atmospheric Pressure on the Bulbs of Ther- 
mometers. — In a preceding Number, vol, viii. p. 397. and vol. ix. 
p. 196., we have noticed the observations of MM. Flauguergues, 
Bellani, and Professor Moll on this subject. The observa- 
tions of M. Flauguergues, induced two young and ingenious 
chemists of Geneva, MM. Aug. De la Rive, and Francis Mar- 
cet, to examine the subject with considerable attention. The 
following are the general results of their experiments. 
1. That atmospheric pressure influences the size of the bulbs of 
thermometers. 
2. That thermometers open at their upper extremity should be 
used in cases where this influence may be sensible. 
