1815.] Analyses of Books. 385" 
the equilibrium of heat in a state of uniform temperature, “as the 
author himself has observed, In fact, these experiments show us 
the evaporation of camphor by the radiation of different bodies pro~ 
rtional to the greater or smaller disposition of these bodies to 
radiate, even when the temperature is uniform ; or, in other terms, 
even when the equilibrium of calorie exists. Hence it follows that 
radiation exists even in this state of equilibrium. ‘This direct expe- 
riment seems to confirm in a satisfactory manner the numerous 
arguments in favour of the theory of the equilibrium of heat. 
The memoir of M. Rubland contains several other interesting 
facts, which appear to me to flow directly from the general laws of 
heat. For example, lamp-black, which is known to be one of the 
most powerful radiators of heat, sublimes or evaporates camphor 
very rapidly. But if a metallic plate is placed over the lamp-black, ' 
the evaporation is immediately retarded. The caloric of the inferior 
strata is intereepted by this screen, or by this change of medium. 
“1 do not choose to enter into further details on this subject, which 
is beyond the particular point of theory that I was anxious to illus- 
trate. 
aoe EE 
ArticLte [X. 
Anatyses or Books. . 
Hints for establishing an Office in Newcastle for collecting and 
recording authentic Information relative to the Stute of the Col- 
lieries in its Neighbourhood, and the Progress that has leen made 
towards ascertaining the Nature and Constiiution of the Strata below 
those Seams to which the Workings in this Country have been con- 
jined. By Wm. Thomas, Esq. Lo which are added Observations 
on the Necessity of adopting legislative Moasures to diminish the 
probability of the recurrence of fatal Accidenis in Collieries, and to. 
prolong the Duration of the Coal Mines of the United Kingdoms. 
By Wm. Chapman, Esq. Civil Engineer. Being two Essays read 
at a Meeting of the Literary and Philosophical Society of New- 
castle-upon-Tyne, and elehed by order of the Society. 1815, 
Tuts pamphlet contains a proposal to establish a Society in New-. 
eastle-upon-'yne, by whom all the facts respecting the collieries on 
the T'yne and Wear are to be collected and registered. When a, 
colliery is abandoned, an exact plan of it is to be.constructed, ex-, 
hibiting those parts in which the coals have been wrought out, and 
those in which they have been abandoned. ‘The consequence of 
this plan would be that by degrees a complete knowledge of all the, 
underground workings would be acquired, It is obvious that all the 
abandoned. collieries must be filled with water, and that unless an 
exact knowledge of them is obtained, it must become more and 
more difficult every year to sink new pits, Indeed the time must 
Vor. VI. N° V. 2B 
