Magnification of sketch
drawn by James Joule in
his letter to William Thomson
March 5th 1863
JOULE'S THERMOSCOPE
Magnification of sketch
drawn by James Joule in
his letter to William Thomson
March 5th 1863
Reference 1 Proceedings of the Literary and Philosophical Society of Manchester
March 11th 1863, Volume 3, p 73-4
Reference 2 Joule's letter to Thomson March 5th 1863
Manuscript Number MS Kelvin J171, by courtesy of Glasgow University Library
Typed transcript of above letter from Joule to Thomson March 5th 1863
Gr Exmouth St
Birkenhead
March 5th 1863
My dear Thomson
I feel now to be amply revenged on Tyndall for I find that the moon is hot not cold as he pretended. If you find space you and Tait must add something to your book on the wind produced by the action of our satellite. I have made my experiment as follows. A glass receiver 2 feet high has a cardboard partition so as to divide it into two parts vertically, but leaving a space of 2 inches at the top and at the bottom. The cardboard is blackened and also two thin pieces placed in each side of the partition. It is evident that if one side is heated this least degree more than the other, the air in it will rise, descending in the other as in a bratticed coal pit shaft. The existence of such a current is made manifest by a magnetic needle an eighth of an inch long ----, furnished with a long glass index and hung by a single filament of silk.
The delicacy of this thermoscope is such that a small blackened pan containing a pint of water heated 30° F placed at 2 yards distance makes the index go through 5° . I have increased the delicacy of the instrument by counteracting the magnetism of this earth, and now by placing it at 2 yards from a shutter with a slit in it and marking the effect of the moon as a beam of its light passes by, I find a distinct effect of about 4° which indicates, as far as I can estimate it at present, that the air on one side of this diaphragm was raised about
1
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10000 of a degree F. I intend to improve on the instrument and make it more useful by the next time we have a full moon.
I am returning from here on Saturday. I must contrive some means of getting our apparatus to work again but I fear it cannot be managed at Thorncliff and I shall have to find some other place in the neighbourhood.
Trusting Mrs Thomson has experienced no ill effects from her alarming accident and with kind regards to her.
believe me
Yours always true
James Joule
Reference 3 Joule's letter to Tyndall, March 23rd 1863
Manuscript Number RI MS JT/1/J/139 by courtesy of
The Royal Institution of Great Britain
Reference 4 A R Bennett, Engineering, Lond., 1897, Volume 63, p239-241
Reference 7 The Scientific Papers of James Prescott Joule Volume 1, p 416-9
London: Dawsons of Pall Mall, 1887
Reference 8 Proceedings of the Literary and Philosophical Society of Manchester
January 26th 1897, Volume 41, pp xxvii-xxviii
