; Yan. He), 1882] 
our scientific terms. In the expression actinism and radiant heat, 
the cause has been mixed up with the effect. To be consistent, 
given one class of bodies the rays falling on it should be 
ealled actinic rays ; whilst, given another, they should be called 
heat rays. 
In 1840 Dr. F. W. Draper, of New York, clearly pointed 
out the identity in quality (if I may so call it) of the light, heat, 
and actinic rays, and that identity, I hold, has been confirmed 
more than once by recent investigators. I speak, perhaps, 
~ somewhat strongly on this point as no one knows better than 
myself the immeasurable mischief which a wrong definition 
causes in the progress of a scientific education. Men matured 
in science can afford to use any definition since they can care- 
fully guard it by mental reservations as to what they really 
understand by it; but I hold it as a misfortune of no mean 
order that definitions, which are not so exact as our present 
state of knowledge can make them, should be given to the 
uninitiated whose reasoning powers must at the outset be feeble. 
A definition containing but half a truth must of necessity lead a 
student of science to a wrong conclusion at some time or 
another. If our writers of text-books could but be persuaded to 
write as they believe in this matter, and as some have written 
(for instance, Clerk Maxwell), we should have fewer mistakes 
made in explaining the ordinary phenomena met with in daily 
life. 
I think I have now explained what I meant when the answer 
was given, ‘‘ There are no such things as heat rays:” a source 
of energy may be darkly hot as was the kettle, some of the energy 
radiating from it was expended in heating bodies round it, but 
that portion which radiated through the holes perforated in the 
card and which struck the plate was, at all events, partially 
expended in converting the silver bromide into the sub- bromide. 
In the course of these lectures, which I now finish, it has 
been my endeavour to show you the principles on which experi- 
ment in the infra-red region has been carried out, and also to 
point out the necessity for further work of no light kind in this 
part of the spectrum. The preceding lectures will also have 
shown you that work is required to investigate the visible 
part of the spectrum, and also in the observation of the various 
phenomena presenting themselves on the solar surface which 
must of necessity react upon our earth, It has been ignorantly 
‘said that the study of solar physics will be exhausted in ten or 
twelve years, but from what you have heard my colleagues tell 
you it will surely last our lifetime. If I live till the exhaustion 
takes place, my allotted threescore and ten years will, I should 
say, be greatly overstepped. I prophesy, though it can hardly 
with decency be called a prophecy, that many generations will 
pass away before all is known of the exact relationship between 
solar and terrestrial phenomena. What we do know already 
is hardly the alphabet of the language in which the sun addresses 
us, and until that alphabet is mastered the whole story that he 
would tell us must remain undeciphered, 
MORPHOLOGY OF THE TEMNOPLEUVURIDE 
“THE following is an abstract of a communication read before 
the Linnean Society, Dec. 15, 1881 :—The Temnopleuridz, a 
sub-family of oligopores, are remarkable for their sutural grooves 
and depressions at the angles of the plates. The author ex- 
amined the grooves and depressions or pits in Sal/macis sulcata, 
Agass, andfound that these last are continued into the test as 
flask shaped cavities sometimes continuous at their bases which 
are close to the inside of the test, but do not perforate. This is 
the case in the median vertical sutures of the interradium and 
ambulacrum. Between the interradium and the poriferous plates 
of the ambulacra are numerous pits in vertical series which are 
the ends of cylinders closed and often curved within. Altogether 
the undermining is considerable. The grooves over the sutural 
margins are losses to the thickness of the test. The edges of the 
contiguous plates are sutured together, by a multitude of knobs 
and sockets y$> of an inch in diameter visible with a hand 
lens, In the vertical sutures there is an alternate development 
of knobs and sockets on each plate corresponding to a similar 
development on the opposed plates. Between the horizontal 
plate edges are sutures remarkable in their distinctness and posi- 
tion. The apical edges of the interradial plates have multitudes 
of sockets and the actinal edges, knobs : whilst the apical edges 
of the ambulacral plates have knobs and the actinal have sockets. 
The ambulacra, on their interradial edge have nothing but knobs 
and the interradial plates corresponding sockets, so that a great 
NATURE 
257 
series of kmobs and socket ‘‘dowelling ” prevails. Zemnopleurus 
torematicus, Agass,, gave similar results modified by the great 
development of the grooves and the young form was shown to 
differ from the adult, and to have rows of knobs and sockets, 
and barely penetrating pits, The arrangement in Sa/macis 
bicolor and Amblypneustes ovum was considered. The pits have 
an importance for they increase the superficies of the derm and 
near the peristome, as indicated by Loven, they contain Spheridia. 
The paucity of knowledge respecting the union of the plates 
of the Echinoidea was noticed and the nature of the suturing of 
Echinus and Diadema was explained, the first resembling part 
of that of a young Zemmnopleurus, but it was without knobs and 
sockets. _The author concluded by separating the Temno- 
pleuridze into two divisions, those with pits and those with 
grooves without pits. The last are the oldest in time and 
resemble young modern forms which subsequently develop pits. 
He reduced the number of genera considerably. 
P. M. DUNCAN 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE 
WE are glad to learn that the number ‘of students who have 
entered the Chemical Laboratory of Firth College, Sheffield, 
this session, has been so great, that the present accommodation 
has been quite insufficient. The Council, therefore, decided at 
their last meeting to erect working benches for sixteen more 
students. The University of Edinburgh have recently recog- 
nised Dr. Carnelly, Professor of Chemistry in Firth College, as 
a Teacher of Medicine in Sheffield, whose lectures on Che- 
mistry, and course of instruction in Practical Chemistry shall 
qualify for graduates in Medicine in that University. The 
lectures on Chemistry and Laboratory Practice at Firth College 
have also been recognised by the Royal College of Surgeons and 
the Royal College of Physicians. 
SCIENTIFIC SERIALS 
American Fournal of Science, October, 1881.—Cause of the 
arid climate of the western portion of the United States, by C. 
E. Dutton.—Embryonic forms of trilobites from the primordial 
rocks of Troy, N.Y., by S. W. Ford.—Observations of 
comet 4, 1881, by E.S. Holden.—Thickness of the ice sheet at 
any latitude, by W. J. McGee.—Notes on earthquakes, by C. 
G. Rockwood, Marine fauna occupying the outer banks off 
the southern coast of New England, by A. E. Verrill.—Note on 
the tail of comet 4 1881, by L. Boss.—Geological relations of 
the limestone belts of Westchester Co. New York, by J. D. 
Dana. 
November, 1881.—Jurassic birds and their allies, by O. C. 
Marsh.—The remarkable aurora of September 12-13, 1881, by 
J. M. Schzberle.—The stereoscope and vision by optic diver- 
gence, by W. L, Stevens.—The electrical resistance and the co- 
efficient of expansion of incandescent platinum, by E. L. Nichols, 
—Local subsidence produced by an ice-sheet, by W. J. McGee. 
—wNotes on the Laramie group of Southern New Mexico, by J. 
J. Stevenson.—Polariscopic observations of comet ¢ 1881, by 
A. W. Wright.—The relative accuracy of different methods of 
determining the solar parallax, by W. Harkness.—The nature 
of Cyathophycus, by C, D. Walcott. 
Fournal of the Franklin Institute, December, 1881.—Report 
of the committee on the precautions to be taken to obviate the 
dangers that may arise from electric lighting.—Report of com- 
mittee on fire-escapes and elevators.—Chemical methods for 
analysing rail steel, by M. Troilius.—Notes on the properties of 
dynamo-electric machines, by E. Thomson.—Blast-furnace 
hearths and linings, by J. Birkinbine.—Sand-filtration at Berlin, 
by W. R. Nichols.—Report of committee on Griscom’s electric 
motor.— Weighing the sun by a soap-bubble, by P. E. Chase. 
Bulletin del’ Académie Royale des Sciences de Belgique, Nos. 9 
and 10,—Afrofos of determination of latitude, by M. Folie.— 
On the origin of Devonian limestones of Belgium, by M. Du- 
pont.—Application of accidental images {second note), by M. 
Plateau.—A means of measuring the flexure of telescopes, by 
M. Rouzean.—On the micaceous substance of veins of Nil St. 
Vincent, by M. Renard.—Reports, &c. 
Archives des Sciences Physiques et Naturelles, December, 1881. 
—International Geological Congress of Bologna, September and 
