288 
SCIENCE. 
serve as an index during the course of his experiment - one 
violin being fixed and the other moving in a grooved slid- 
ing rest. The second string was then vibrated in a uni- 
form manner, which produced an oscillatory motion, 
which was heard on the corresponding string of the other 
violin. The paper on the string showed the vibration at 
a distance, and the violins were separated from each 
other until the agitation of the paper ceased. This point 
was marked as the limit of the vibrations and marked 
ioo, the intermediate portion being marked off to repre- 
sent the one thousandth part of the distance. 
Experiments made at noon with this instrument, and 
often repeated, indicated the same distance within a few 
thousandths. The whole extent of the scale was 
seven feet, and this distance was the limit of the greatest 
propagation of sound under the influence of light in the 
apparatus. Parolette further states that experiments in 
darkness gave, as a result, a mean temperature of 0.98, 
and that the mean difference of this propogation at noon 
and midnight was two degrees on the scale. In conclu- 
sion, Parolette tries to explain the results arrived at by 
stating that during the day, the atmosphere is more nearly 
saturated with oxygen than in the night, but he says it re- 
mains to be proved that this excess is sufficient to cause 
such a difference in the propagation of sound during the 
two periods, and adds, “ rather, may not light be the true 
cause of this increased propaga'ion in oxygen and nitrous 
gas ; as it is known that the former has a great capacity 
for light, and the latter cannot be formed without its 
presence.” As the velocity of light is 900,000 times 
greater than that of sound, it does not appear unreasona- 
ble to explain, in this way, its effects on the vibrations 
which proceed from sonorous bodies. J. M. 
THE NATIONAL ACADEMY OF SCIENCES. 
As the meeting held on the 16th of November last, and 
those of the three following days, were devoted to the 
reading of scientific papers only, little executive business 
was transacted and no new members were elected. 
At the meeting of the Council the following deaths of 
members were announced : 
J. Homer Lane, of Washington, in May. S. S. Halde- 
man, of Chickies, Pa., in September, and Count L. S. 
Portales, of Cambridge, Mass., in October. 
The decease of Professor Benjamin Peirce, of Harvard 
College, one of the original active members of the 
Academy, but whose connection with it had been severed, 
was also announced. 
Resolutions, thanking the T rustees of Columbia College 
for providing rooms for the meeting, and to President 
Barnard and officers of the college and other members of 
the Academy in New York for liberal entertainment of its 
members, were adopted. 
THE FOLLOWING PAPERS WERE PRESENTED : 
1. On the Basin of the Gulf of Mexico. — J. E. Hilgard. 
2. On the Origin of the Coral Reefs of the Yucatan 
and Florida Banks. — Alexander Agassiz. 
3. Observations on Ice and Icebergs in the Polar 
Regions. — F. Schwatka. 
4. On the Duration of the Arctic Winter. — F. Schwatka. 
5. Mineralogical Notes. — Benjamin Silliman. 
6. The Relationship of the Carboniferous Euphoberia 
to living and extinct Myriapods. — Samuel H. Scudder. 
7. Report on the Dredging Cruise of the U. S. Steamer 
Blake, Commander Bartlett, during the Summer of 
1880. — Alexander Agassiz. 
8. On Some Recent Experiments in Determining the 
Electro Motive Force of the Brush Dynamo-electric 
Lamps operating by Incandescence. — Henry Morton. 
9. On the Intimate Structure of certain Mineral Veins. 
— Benjamin Silliman. 
10. On the Ellipticity of the Earth as Deduced from 
Pendulum Experiments. — C. S, Peirce. 
11. On an Improvement in the Sprengel Air Pump. — 
O. N. Rood. 
12. On the Thermal Balance. — S. P. Langley. 
13. On the Measurment of Radiant Energy. — S. P. 
Langley. 
14. Causes which Determine the Progressive Move- 
ments of Storms. — Elias Loomis. 
15. On the Antimony Mines of Southern Utah. — J. S. 
Newberry. 
16. On the Conglomerate Ore Deposits of the United 
States and Mexico. — J. S. Newberry. 
17. On Photographing the Nebula in Orion. — Henry 
Draper. 
18. On Condensers for Currents of High Potential. — 
George F. Barker. 
19. On Sigsbee’s Gravitating Trap. — Alexander 
Agassiz. 
20. On the Deposits of Crystalline Iron Ores of Utah. 
— J. S. Newberry. 
21. On the Origin of Anthracite. — T. Sterry Hunt. 
22. On the Star-List of Abul Hassan. — C. H. F. Peters. 
23. Dimensions of the Brain and Spinal Cord in some 
extinct Reptiles.- O. C. Marsh. 
24. On the Rimravidae. -E. D. Cope. 
25. On the Miocene Canidae. — E. D. Cope. 
26. On a New General Method in Analysis. — Wolcott 
Gibbs. 
27. Note on the Relations of the Oneonta and Mon- 
trose Sandstones with the Sandstones of the Catskill 
Mountains. — James Hall. 
ON THE MEASUREMENT OF RADIANT 
ENERGY.* 
By Prof. S. P. Langley. 
Sir William Herschel showed that a thermometer indi- 
cated more heat beyond the darkest red of the spectrum 
of a prism than in the brightest part of the color ; there- 
fore, he concluded that light and heat were essentially 
different things. This view has apparently been con- 
firmed by numerous other European experiments, and 
has been set forth in all but the most recent text-books, 
where different curves are drawn to exhibit the light and 
the heat of the sun. Of late years many leading minds 
have recognized that these were only different manifesta- 
tions of radiant energy. Prominent among these is Dr. 
John W. Draper, who asserted this principle long ago, 
and who has always maintained that if the heat in a 
pure diffraction spectrum could be accurately measured, 
its distribution would be found almost identical with 
that of light. This was an experiment, which, however, 
could never have been satisfactorily performed had it not 
been for the skill of Lewis M. Rutherfurd, Esq., of this 
city, who has made at his private expense the exquisitely 
delicate apparatus which can produce pure spectra, with 
a success far greater than any attained by the most 
skillful professional artisans of Europe. 
By the use of one of these “gratings,” made on Mr. 
Rutherford’s engine by Chapman, and the employment 
of the thermal balance described in another paper, I 
succeeded in obtaining for the first time full and exact 
measurements of the distribution of energy in a pure 
spectrum, where no lens or prism had been used, and of 
fixing its relative amount, as determined accurately by 
the wave-lengths of light in all parts of the visible spec- 
trum and in the ultra red. It remained to make some 
minute corrections for the selective absorbtions of the 
reflecting apparatus employed. The essential result, 
however, is of high theoretical interest ; it is, that heat 
and light as received from the sun are now experiment- 
ally proved, so far as such measurements can prove it, to 
be in essence the same thing. The old delineations of 
* Read before the National Academy of Sciences, N. Y., 1880. 
