84 



THE BEE-KEEPERS' REVIEW. 



Heat and Its Conduction. 



B. COKNEIL. 



J'EAT, the manner in which it is con- 

 ducted, and the value of different 

 materials as conductors, form a topic 

 of much importance to bee keepers. There 

 is no season when heat does not have some 

 bearing upon apiculture, and we take pleas- 

 ure in laying before our readers some of the 

 correspondence and extracts sent us by Mr. 



Corneil : — 



Lindsay, April 9th, 1890. 

 W. Z. Hutchinson : 



Deae Sik, — In reply to your favor of tlie 

 4th inst., I have to say that, as the time for 

 making up the Review is probably short, it 

 occurred to me that you might not have 

 time to procure the works to which I might 

 have more concisely referred you, so I have 

 taken the trouble to make the extracts which 

 it seemed to me you need, and I think you 

 will now be able to '• speak by the book." 



I have underlined the most important 

 parts in the extract from Tyndall, and these 

 cover the case exactly. The only other mod- 

 ifying circumstance besides the nature of 

 tlie material, is the quality of transmitting 

 tlie moistuTe instead of retaining it. Cork 

 dust and sheep's wool are ahead in this 

 respect. Perhaps you will notice that the 

 table from Schumann's work places cork 

 dust lower as a non-conductor than is done 

 by Cheshire or the compiler in the table in 

 the Eucy' Britt. 1 am of the opinion that, 

 unless the figure given by Schumann refers 

 to a solid plate of cork, as I believe it does, 

 he is mistaken. 



I have great faith in straw. I have sixty- 

 two hives having walls of straw a little over 

 one inch thick. Most of them are lined with 

 carpet-felt paper three plies thick, and in- 

 side of that a sheet of wood ^s inch tliick. 

 I have forty others with an outside shell of 

 % pine, l^^fj inch cork, and the same lining 

 as the straw. I believe I have the warmest 

 hives in America without their being cum- 

 bersome. See the tallies on the non-con- 

 ductivity of blotting paper. 



By the way, the reporter at the " Interna- 

 tional " makes me talk aVjout having hive 

 walls thick. I didn't say that. I said by 

 having them warm enough, a very different 

 thing. And in my paper, page 12, report, 

 there is a typographical error in the first 

 line, first column, page 13, " zinc " was 

 " pine " in the paper. The A. B. J. and the 

 C. B. J. both have the error, but the Guide, 

 using a copy from the type writer, made 

 simultaneously, has it correctly stated. 

 These errors are eclipsed, however, by the 

 committee who reported on exhibits, when 

 they said I exhibited part of a hive made of 

 " wired '^ straw. There was no "wire" 

 about it. It was sewed with cane. I pur- 

 posed correcting these errors in the A. B. J. 

 and C. B. ./., but neglected doing so. 



Hoping the extracts I enclose herewith 

 will be about what you require, I am, dear 

 sir, Yours truly, 



S. COKNEIIi. 



FBOM "heat as a MODE OF MOTION," BY 

 JOHN TYNDALL, F. B. S., PAGE 24(5. 



" The indefatigable Rumford made an 

 elaborate series of experiments on the con- 

 ductivities of the substances used in clothing. 

 His method was this : A mercurial thermom- 

 etor was suspended in the axis of a cylindri- 

 cal glass tube ending with a globe, in such a 

 manner that the center of the bulb of the 

 thermometer occupied the center of the 

 globe ; the space between the internal sur- 

 face of the globe and the bulb were filled 

 with the substance whose conductive power 

 was to be determined ; the instrument was 

 then heated in boiling water and afterwards 

 being plunged into a freezing mixture of 

 pounded ice and salt, the times of cooling 

 down 185° Fah. were noted. They are re- 

 corded in the following table : — 

 Surrounded with Seconds. 



Twisted silk 917 



Fine lint 1032 



Cotton wool 104G 



Sheep'' s ivuol 1018 



Raw silk 1264 



Beaver's fur 1296 



Eider down i:*."! 



Hare's fur 1312 



Wood ashes 927 



Charcoal 937 



Lampblack 1117 



Page 247. The transimssion of heat is 

 pouwrfulhj injiuenced by the mechanical 

 state of tlie body throwjii wJiich it jiasses. 

 The raw and tivisfed silk of Rumford^ s table 

 illustrates this. * * * * Through trans- 

 parent rock salt heat is copiously conducted, 

 tlirouyh conunon salt rei-y feebbj. I have 

 here some asbestos, which is composed of 

 certain sillicates in a fibrous condition : I 

 place it on my hand and on it place a red hot 

 iron ball ; you see I can support the ball 

 without inconvenience. The asbestos intei'- 

 cepts the heat. That this division of the 

 sid>stance should interfere icith the trans- 

 mission might reasonably be inferred : for 

 heat being motion, anything which disturbs 

 the continuity of the molecular chain along 

 which tlie motion is conveyed )nust affect the 

 transmission. In the case of the asbestos 

 the fibers of the silicates are separated from 

 each other by spaces of air : to propagate 

 itself therefore the motion has to pass from 

 the silicate to the air, a very light body, and 

 again from the air to the silicate, a very 

 heavy body ; and it is e(tsy to see that the 

 transmission of motion tlirough this compos- 

 ite tejcture must be rerij iniperfect. In the 

 case of an animal's fur this is more especially 

 the case ; for here not only do the spaces of 

 air intervene between the hairs, /;!(^ the hairs 

 them.<<elves, unlike the fibers of the ai^bestos, 

 are very bad conductors. 



From Manual of Heating and Ventilation, 

 by F. Schumann, page r^7 : 



CONDUCTING POWER OF MATERIALS. 



Value of C. being the units of heat trans- 

 mitted per hour per square foot of a plate of 

 the material one inch thick, the two sur- 

 faces differing in temperature one degree. 



