EXPANSION OF BODIES BY KEAT. 
47 
are 7 orbs, which are the seven stars, the 
pleiades, theSuccoth penneth, or ients of the 
(laughters in Scripture, called genial andexhi- 
ting stars, and are shedding their inHuence- 
over the dove, 
I'he face of the monarch is towards the east, 
and thestars are placed on the eastofthe mo- 
nument, rising with Aldebaran. 1 wo larger 
orbs represent the sun and moon, supplied with 
wings similar to the sculptures of Persepolis. 
There is still another star which is probably 
Venus, the morning star. Mr, Landseer from 
tliese and similar data, concluiies that this mo- 
numentwas sculptured in the time of Pelassar 
or Salmanassar, twenty-five centuries ago. 
Another monument of which a drawing by Be- 
nomi was exhibited, contains on its margin the 
hieroglyphical nameof Sesostris, identical vvith 
that which exists on the table of Abydos. The 
sculpture. represents the figure of a man holding 
a bow in his right hand and a battle-axe in his 
left, in the act of offering prisoners to a deity. 
Herodotus describes an Ionian monument almost 
identical with this. Another of themonuments 
observed near Sidon, relates the circumstance 
of Antoninus having altered the road along the 
coast, the former road having been at a greater 
elevation. 
In the course of his lecture, Mr La,ndseer 
displayed an intimate acquaintance with sa- 
cred and profane history, and shewed that his 
mind was keenly alive to the refinements of li- 
terature, In some of the poetic flights in 
which he frequently indulged, we were 
brought back to tho.se ancient times, when 
the kindly influences of the heavenly orbs pre- 
sided over liuman destinies, and the descrip- 
tions miglit have^lmost induced the sanguine 
to regret, that such mysterious days have pas- 
sed away. 
AN ABSTRACT OF SOME RESEAR- 
CHES ON THE REPULSION PRO- 
DUCED BETWEEN BODIES BY THE 
ACTION OF HEAT WITH ADDITION- 
AL OBSERVATIONS. 
By the Reverend Baden Powell, 
M. A., F. R. S., 
Savilian Professor of Geometry, Oxford. 
The curious point to which my attention 
has been directed, is one of those whi ch too 
generally fail in securing the attention of 
philosophers, from the circumstance that 
they belong to a class of phenomena hardly 
coming within the specific range of any one 
of the great divdsions of Science ; or rather, 
belonging equally to several, are but little 
considered in any. In the “ Records of 
General Science,” however, some account of 
them may perhaps find a place. 
At the meeting of the British Association 
at Edinbur-gh, 1 gave a short statement of the 
experiments which I had made : an account 
of them was also read before the Royal So- 
ciety, and is now printed in the Philosophical 
Transactions for 18114. But a brief outline of 
their nature and object may not be unaccep- 
table to some readers, especially as it will 
be essential to render intelligible the further 
observations I wish to add. 
The expansion of bodies by heat seems to 
imply a mutual repulsion of their particles ; 
and it is a question naturally suggested, whe- 
ther such a power of repulsion may not 
generally belong to heat, or be excited by it 
between particles or masse.s of matter at 
sensible as well as insensible distances. But, 
however obvious the suggestion of such an 
inquiry, it is of a nature not easy to be pur- 
sued or decided. 
The subiect has been partially investigated 
by Sig. Libri, and by M. M. Fresnel and 
Saigey ; but their researches do not appear 
to have been regarded as decisive, and have 
ever been viewed with considerable doubt ; 
and they are certainly dependant upon ex- 
periments of the most extremely delicate and 
difficult kind, and those of Fresnel confessedly 
left in an incomplete state. 
Recently, the inquiry has been revived by 
Professor Forbes of Edinburgh, who has 
referred to the same principle to account for 
the singular phenomena of certain vibrations 
of heated metallic bars, first noticed by Mr. 
Trevelyan, and since fully investigated by 
himself in a paper in the Edinb. Trans. 
vol. xii. 
In a different form the subject had occupied 
my attention before I was acquainted with 
Professor Forbes’s investigations ; but, on 
reading his paper*, a new interest attached to 
the inquiry, and in pursuing it, I conceive I 
have obtained some results which appear 
decisive on a question at once of importance 
in the analogies of physical action, and which 
has hitherto been regarded as at least involved 
in considerable uncertainty. 
The method 1 pursued was that of forming 
Newton’s rings between lenses, and apply- 
ing heat, w hich would afford a simple mode 
of deciding the question, if there be any 
separation of the glasses by repulsion, since 
it would be rendered visible by the contrac- 
tion of the rings. As to the error which might 
arise from the warding of the upper glass by 
the heat, it wall be evident, on a little consi- 
deration, that heat applied outside of either 
glass will tend, by the change of figure, in 
every case, the first instance, to diminish the 
angle of contact; that is, if no other cause 
interfere, to make the rings enlarge without 
altering the central tint, until the curvature 
become equal to that of the convex surface. 
I invariably found, how'ever, that/rowe the 
first moment the rings regularly contract, 
and the central tint descends in the scale 
till the whole vanishes. There are, how- 
ever, several precautions necessary to be 
attended to. If the glasses be more than 
very slightly convex, the portion of surface 
throughout, wffiich they approach sufficiently 
near for the repulsion to act, is very small. 
This may render the total effect far too 
weak to overcome the w^eight of the upper 
glass, or even its inertia, though placed 
vertically. With surfaces of such curvature 
as to give the first bright ring a diameter of 
about ()*3 inch, on placing a red hot poker a 
little above the glasses the effect never failed 
to be produced. Upon the whole, the ex- 
