144: 



REPORT — 1881. 



Forbes, G. ib. 62. — Conductivity of ice and other substances. Kate of formation of 

 plate of ice measured, formed in water of 0° C. by vessel with flat bottom con- 

 taining freezing mixture. Similar method adopted for other substances. Results 

 (cg.s.) 



Ice, par. to axis 

 „ perp. to axis 

 Black marble 

 Wliite „ 

 Slate . 

 Snow . 

 Cork . 

 Glass . 

 Pasteboard 

 Carbon 

 Roofing felt 

 Firwood, ax. 



tang. 

 Boiler cement 

 Paraffin 

 Sand . 

 Sawdust 



•00223 

 •00213 

 •00177 

 •00115 

 •00081 

 •00072 

 •00072 

 •00050 

 ■00045 

 •00040 

 •00033 

 •00030 

 •00009 

 •00016 

 •00014 

 •00013 

 •00012 



Figures all very low, save that the one for ice agrees with De la Eive's. 

 Figures for quartz show conductivity five times as great across axis as along it. 



Playfair, ' Trans. R.S.E.' 6, 353 (1812). — Cooling of a sphere. Simple mathematical 

 treatment of the question of terrestrial temperature. 



Forbes, ' Trans. R.S.E.' 23, 133 (1862) and 24, 73 (1865). c. ' Proc' 4, 607 and 5, 369. 

 Details of experimental method and of the calculation of the results. 



Helmersen, ' Ann. Chim. Phys.' (3), 46, 126 (1856).— Eocks (from Altai). Despretz' 

 method : bars, 456'""'^ x 38°""- square ; four thermometers 67""'"^ apart, and holes 

 filled with Hg ; bars covered with black to equal surface ; hot end in contact 

 with boiling H,0. 



' The average values here found differ (as above described in this report) from 

 those entered in the general list, in being obtained fi^om the three successive ob- 

 served thermometric intervals ; wliile those adopted in the list are simUai^ly deduced 

 from the three temperature-intervals all reckoned /w?^ the first, or hottest of the 

 four thermometric readings Vx-t',- 



