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| ¥une 26, 1873] 
NATURE 
173 
THE following additions have been made to the Brighton 
Aquarium during the past week :—Two Puffins (Fratercula 
arctica) ; small Crocodile (Crocozilus sp.) from Sumatra, pre- 
-sented by Captain Murray ; Bass (Zedrax /upus); Black Bream 
(Cantharus lineatus); Streaked Gurnards (Zrigla lineata) ; 
Mackerel (Scomber scomber); Lumpfish (Cyelopterus /umpus) ; 
Grey Mullet (AZugil capito) ; Ballan Wrasse (Zadrus maculatus) ; 
Flounders (Pleuronectes flesus), fresh-water variety, presented by 
F. J. Evans, Esq. ; Herring (Clupea harengus) ; Conger Eels 
(Conger vulgaris); John Dorée (Zeus faber); Sea Horses 
(Hippocampus ramulosus) from the Mediterranean ; Octopus 
(Octopus vulgaris) ; Oysters (Ostrea edulis); Zoophytes (Actinoloba 
dianthus), (Sagartia nivea), (S. miniata), (Alcyonium digitatum), 
( Zubularia indivisa). 
THE additions to the Zoological Society’s Gardens during the 
past week include a Dormouse Phalanger (Dromicia nana) from 
Tasmania, presented by Mast. W. F. Stratford ; a Coati, brown 
variety (Vasua nasica) from S. America, presented by Mr, G. P. 
Crawford; a Lion (fis Jeo) from Africa, presented by the 
Hon. M. E.G. Finch Hatton; a Rhesus Monkey (MJacacus 
erythreus) from India, presented by Mr. J. C. Freeman; a 
Tasmanian Rat Kangaroo (Hyfsifrymnus cuniculus), presented 
by Mr. J. Shelton ; a Garnet’s Galago (Ga/ago garnetti) from 
E, Africa, presented by Mr. Bartle Frere ; two horned Lizards 
(Phryrosoma cornutum) from Texas, presented by Mr. W. L. 
Booker; a Clifford’s Snake (Zamenis cliffordiit) from Cairo, 
‘presented by Mrs. E. Liveing ; a black Stork (Ciconia nigra), two 
white Storks (C. a/éa), and a Spoon-bill (Platalea leucorodia), 
purchased ; a red Kangaroo (Macropus rufus), and a Fallow 
Deer (Dama vulgaris), born in the Gardens. 
SOCIETIES AND ACADEMIES 
LonDoN 
Royal Society, May 15.—‘‘ On the Heating of a Disc by 
Rapid Rotation zz vacuo.” By Prof. Balfour Stewart, M.A., 
F.R.S., and Prof. P. G. Tait, M.A. 
In two previous communications to this Society, we gave an 
account of some experiments which we had made up n the 
heating of a disc through rotation 7 vacuo. In these experi- 
ments the increase of radiation of the heated disc was observed 
by means of a delicate thermopile and galvanometer. Three 
aluminium discs of various thicknesses and one ebonite disc 
were used, and the results derived from the experiments were as 
follows :— 
(1) The heating effect observed appeared to be independent 
of the density , and of the chemical constitution of the residual 
air and vapour surr ounding the discs. ; 
(2) The quantity of heat developed under similar circum- 
stances of rotation in three aluminium discs ‘05, ‘0375, ‘025 of 
an inch in thickness respectively appeared to be the same, inas- 
much as the relative thermometric effect for these discs varied 
inversely as their thickness. 
(3) Besides the heating effect alluded to in (1) and (2), there 
was found to be, when the vacuum had been recently made, a 
strictly temporary effect, sometimes in the direction of heat, 
sometimes in that of cold, owing probably to the condensation 
or evaporation of small quantities of aqueous vapour ; but this 
effect was only noticeable during rotation, disappearing the mo- 
ment the motion was stop ped. 
In June 1871 the expe riments were resumed. In the mean time 
theapparatus had been fitted with an arrangement working through 
a barometer-tube, by means of which, instead of trusting to radi- 
ation, the disc itself might, after rotation, be tapped by means 
of the pile, which could be brought up to it and then withdrawn. 
By this means a much larger effect. might be obtained, and it 
became possible, by varying the adjustment, to find according to 
what law the heat-effect varies with the distance from the 
centre. 
These experiments were conducted in the following manner : 
_The disc was first of all tapped before rotation several times ; 
at each tapping the momentary swing of the needle was re- 
4 
= = i bd 
corded, and the mean of the readings was regarded as indi- 
cating the state of the disc with respect to heat. 
The disc was next tapped after rotation, and the difference 
between the readings before and afier was taken as indicating the 
change in the state of the disc produced by rotation. 
The results derived by tapping an ebonite disc were found to 
be very different from the radiation-results, inasmuch as in the 
former the effect of the pressure and quality of the residual air 
is very apparent, while in the radiation-results it is hardly per- 
ceptible. A probable explanation of this will be given after- 
wards, but in the mean time, in view of these results, it has been 
thought expedient to discuss them quite independently and by 
themselves, with the view of ascertaming whether they can_ best 
be explained by a gas-effect alone, or whether they likewise indi- 
cate a residual effect independent of gas, 
With this object calling A B the results at and .3, let us 
take een) : (B) 
of 35 in. due to whatever cause or causes. 
as representing the whole effect at a pressure 
We thus obtain 
Dry hydrogen. Dry air. Dry carbonic acid. 
Whole effect at . 9°5 250 24'0 
Again, let us suppose that (A)—(B) denotes the gas effect for +, 
in., and we obtain 
Dry hydrogen. Dry air. Dry carbonic acid. 
Gas-effect at 40 20°0 18'0 
Finally, let us regard as unknown residual effect the difference 
between the whole effect and the gas-effect, and we obtain 
Dry hydrogen. Dry air. Dry carbonic acid 
Residual effect 55 50 ‘oO 
Similar experiments with the same galvanometer were made 
with a disc of cartridge-paper, of which the pores were filled 
with solid paraffin. 
Treating these results in the same manner as those of the 
ebonite disc, we obtain :— 
Dry hydrogen. Dry air. Dry carbonic acid, 
Whole effect (~%;) 25'0 45°0 43°5 
Gas-effect (x) . . 4'0 20°0 230 
Residual effect 21'0 250 20°5 
Now, if we suppose that there is only one effect due to gas, it 
follows :— 
(a) That the proportion between the effects due to the various 
gases experimented on (and all of the same pressure) is never- 
theless different for the two discs. 
(8) That the proportion (for the same disc) between the effects 
due to the various gases experimented on is different according 
to the pressure. 
If, however, we suppose that there are two effects, one of 
which is independent of the residual gas, we find :— 
(a) That, as regards the gas-effect, the proportion between that 
due to the various gases is nearly the same for both discs. Thus 
in the ebonite disc we have 4, 20, 18, while in the paper disc we 
have 4, 20, 23 as representing the gas-effect for the various 
gases, 
(8) That the vestdual effect in either disc is nearly the same for 
the various gases. Thus in the ebonite disc we have 5°5, 5'0, 
6'0, while in the paper disc we have 21°0, 25°0, 20°5 as repre- 
senting the residual effect for the various gases. 
The results are thus much more simple on the hypothesis of 
two effects, one of these being independent of the residual gas, 
than on the hypothesis of only one effect. 
It was next endeavoured to ascertain whether these two effects 
were differently influenced by a blind, and it was found that the 
proportion between the two effects is greatly altered by the blind, 
so that while the hydrogen effect is not much stopped, the other 
is diminished very considerably ; it was therefore concluded that 
the residual effect is not much altered by a chamois leather 
blind. 
It was suggested to us by Prof. Helmholtz that it would be 
desirable to ascertain whether any difference was produced in 
the results by loading the disc on one side; for if these 
results be due to vibration, it might be supposed that they would 
be affected by this means. 
It has been seen that the residual effect obtained from a disc 
covered with chamois leather is approximately the same as that 
from an uncovered disc ; this would appear to us to be against 
the vibration hypothesis. 
In an experiment made the disc was covered with a chamois 
leather blind with a segment cut out. 4 
