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Art. XXVII— SCIENTIFIC INTELLIGENCE. 
METEOROLOGY. 
1. Hygrometer . — It is known, that, if a thermometer, after its 
bulb has been immersed in sulphuric acid, is exposed to the 
air, the mercury rises for some time, and then sinks again, to 
the degree it had before immersion in the acid. The increase 
of temperature is owing principally to the absorption, by the 
acid, of the water of the atmosphere; hence it has been proposed 
to use this change of temperature, as a means of determining the 
moisture of the air. M. Professor de la Rive’s amusing paper 
on this subject, having reached us too late for our present publi- 
cation, must be delayed until the next. 
Meteoric appearance on Ben-Lomond and Loch-Lomond 
“ On Sunday, May 8th, I set out, accompanied by my friend Mr 
Savage, at three o’clock in the morning, to ascend Ben-Lomond, 
and, if possible, arrive at its summit before sunrise. The mor- 
ning was unfavourable, — the wind, blowing from the south-west, 
was cold and damp, — the sky on that quarter was every where 
covered with dark and dense clouds, which seemed crowding to- 
wards the towering summits of the surrounding hills, leaving the 
Isles of Arran and Bute, the mouth of the Clyde, and Loch-Lo- 
mond, in dreary and dismal darkness. Towards the east, a 
small extent of deep-azured sky was to be seen ; but even there, 
a number of cumuli and cirri were rapidly forming, and nume- 
ous variously shaped white-edged cumuli-strata, and more dense 
nimbi. A short time after this, it began raining, and continued 
incessantly for the space of nearly two hours ; during which 
time we sheltered ourselves principally under the rugged cliffs of 
mica slate, of which the summit of this celebrated moun- 
tain is composed. Taking advantage of the first interval of fine 
weather, we again attempted to ascend the steep sides, and gain 
the wished-for top. The clouds soon broke, and allowed the sun 
to dazzle forth in all its splendour, upon the steep, though ro- 
mantic, declivity beneath our feet. It was about this time, ha- 
ving our faces turned towards the west, that we observed streams 
of vapour rise from the earth in two or three places (at about a 
mile distance from us, and 400 or 500 yards apart from one ano- 
ther), and ascend in a perfectly straight direction towards a 
heavy dark nimbus passing over at the time. LTsing my hat as 
