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Scientific Intelligence. 
[Oct. 
the sponge the temperature falls, and if the air be not very dry, moisture will be de- 
posited on the outside of the glass tube, where the sponge is in contact. The ther- 
mometer is then read off, and must give the temperature of the tube on which the 
dew has condensed, and consequently the temperature of the. dew itself. If the air 
be dry and the action of the instrument sluggish, a blast of air driven by a small 
bellows through the tube, will accelerate the process. Mr. Cumming’s arrange- 
ment appears to us to be convenient ; it can easily be tried by any one who has one of 
those thermometers' enclosed in a cylindrical glass tube (which are so common in In- 
dia), a little ether, and a bit of sponge. If the tube be not open below, a piece may 
be easily cut off with a file. 
Our readers are sufficiently aware, that the observation of the dew point is the 
only certain means we have of measuring the h umidity or dryness of the air. Every 
other hygrometer is only useful in as much as it enables us to determine this point, 
however indirectly. The observation of the dewpoint must then always be the 
test of accuracy of every hygrometer : it enables us in fact to form a standard, with 
which we can compare the indications of every instrument proposed for measuring 
the humidity of the air. Daniel’s hygrometer offers certainly, a neat and elegant 
method of performing the experiment. Yet it must be confessed, that it is too ex- 
pensive ever to come into general use. Mr. Cumming’s modification of the ar- 
rangement, places within the reach of most observers, the means of making obser- 
vations which the scientific metereologist must frequently have recourse to, what- 
ever instrument he use for the ordinary indications. D. 
3. Mr. Wheatstone's Microphone. 
This instrument consists of two plates of metal, of one inch in size, so as to cover 
the cavities of the ears ; each plate has a wire about one-eighth of an inch in dia- 
meter, rivetted at one end at right angles into its centre : the wires being about 
eighteen inches long, are bent round, a little distance from the plates, and brought 
together side by side at the extremities, where they are united by brazing, and 
jointly filed to a point. When tkif instrument is used, the plates are put over the 
ears, the spring of the wires holding them with sufficient force against the head ; 
the point or apex of the microphone, is then to be brought into contact with any 
part, the phonic vibrations of which are to be ascertained. The vibrations are con- 
ducted along the wire, and being communicated to the plates which close the ears, 
these vibrations are reciprocated by the enclosed volumes of air, and the nerves of 
the ears powerfully affected. By the use of this instrument, the vibrating parts of 
the sounding board of a guitar, harp, or other instrument, can be at once ascertained, 
and the irregular sources of noise and mechanical action in machinery discovered, 
when every other trial has failed. So powerful is the effect of the microphone up- 
on the ear, that by it the most uninitiated can at once be made to perceive the 
effect of chord and discord. 
2.— Miscellaneous Notices. 
1. Dr. Thomson, and Professor Berzelius. 
Dr. Thomson, the well known author of a System of Chemistry, in 4 vols. having re- 
cently published a new work, entitled, An attempt to establish the first principles of 
Chemistry, consisting chielly of determinations of the proportionate weights in which 
bodies combine, or as they are called chemical equivalents ; Professor Berze- 
lius of Stockholm has published some very severe strictures on it, not hesitating 
even to accuse the Doctor of falsifying results, or as a more homely word would 
better express it, of screwing, so as to bring them to the standard of his theoretical 
notions. Dr. Thomson has published in the Annals for Marcli his answer — giv- 
ing various particnlars of his analyses and details of his mode of proceeding, with 
which we shall not trouble our readers. — “ Non nostri est tanlas componere lites 
One remark only we shall make. The editors of the Annals, and Dr. Thomson 
himself, seem greatly scandalised at the charge ofBerzelius as implying a mala fides, 
or want of common honour and honesty. But “ ’twere to consider too curiously 
to consider so.” — We know in how gentle, yet persuasive a manner the genius 
of hypothesis can mislead her votaries ; and when we refer to the history of the 
many serious scrapes into which the unwary amongst them have fallen, from the 
tricks of this Will o’tlie wisp, we cannot but smile at an attempt to magnify the 
