APRIL 19, 1912] 
melt a coating of ice one inch in thickness in 
two hours and a quarter. Langley, about 
1880 devised the “bolometer,” an electrical 
thermometer so delicate that differences of 
temperature of less than one hundred-mil- 
lionth of a degree can be detected. This in- 
strument, as perfected and used by Langley 
and Abbot, has revolutionized the methods of 
studying the character and amount of heat 
received from the sun. The latest researches 
of Abbot and the Smithsonian Institution show 
that if the sun’s rays could be completely em- 
ployed to melt ice they would suffice to melt 
a coating one inch thick in one hour and 
thirty-eight minutes, or a layer 426 feet thick 
in a year. 
Abbot’s book is a study of the latest re- 
searches on the light and heat of the sun, of 
the sources from which that body derives its 
apparently inexhaustible supply of energy, 
and of the methods and instruments by means 
of which the great advances in knowledge 
have been made. It is a book by an active 
and successful worker in the field of solar in- 
vestigation, a particularly sane and success- 
ful worker. The simple astronomical facts 
regarding the size, shape and distance of the 
sun, the phenomena of the visible surface, the 
rotation and the spots, are reviewed at length, 
but the feature of the book is the exhaustive 
treatment of all questions connected with the 
sun’s action as a fountain of light and heat. 
As to what the sun really is, Abbot is a 
strong advocate of the theory of a purely 
gaseous body (except sun spots). That the 
sun is mainly gaseous has been the accepted 
theory, but most writers and investigators 
have considered the visible surface as semi- 
fluid, as a sort of cloudlike formation floating 
in the outer gaseous envelopes. Sunspots 
are regarded by Abbot as cyclonic storms, or 
vortices, similar in form to water spouts seen 
at sea, the whirl carrying gases from below 
upward. The rapid uprush of the gases and 
the spreading out into the trumpet shape top, 
cause a rapid expansion and great cooling. 
This cooling carries the temperature down, 
and allows the formation of liquids, and thus 
the spots may be cloudlike forms, with some 
SCIENCE 
631 
liquid and even solid particles. The peculiar 
periodicity of the spots in number and size 
is as yet unexplained. As to the source of the 
sun’s heat and energy, Abbot shows that we 
may still regard MHelmholtz’s contractive 
hypothesis as adequate to satisfy the require- 
ments of geology and physics. He is not 
earried off his feet by the popular scientific 
craze of explaining everything as a phase of 
radio-activity. Radio-active processes may 
have contributed somewhat to the store of 
solar energy, but that they have been any 
appreciable factor has not yet been shown. 
The book is well written and is full of in- 
teresting matter for the scientist and for the 
general student. In it are tabulated and 
brought - together the results of many re- 
searches, some hitherto unpublished, and 
others only to be found in special journals; 
the various hypotheses of solar physics are 
clearly set forth, and the merits and defects 
of each explained. It is the best work on the 
subject that has appeared for many years and 
will rank with and take the place of the sim- 
ilar book, by the late Charles A. Young, 
which for so many years was regarded as the 
standard treatise on “The Sun.” 
CHARLES Lane Poor 
COLUMBIA UNIVERSITY 
SCIENTIFIC JOURNALS AND ARTICLES 
Tur March issue of Terrestrial Magnetism 
and Atmospheric Electricity contains the fol- 
lowing articles: 
“‘Ueber den elektrischen Strom Erde-Luft und 
seinen Zusammenhang mit den Erdstrémen und 
den Schwankungen des erdmagnetischen Feldes,’’ 
A. Gockel. 
“‘Results of Magnetic Observations made by the 
United States Coast and Geodetic Survey at the 
Time of the Solar Eclipse of April 28, 1911,’’ 
O. H. Tittmann. 
“‘Magnetie Declinations and Chart Corrections 
in the Indian Ocean Continued,’’ L. A. Bauer and 
W. J. Peters. 
“‘Die Verteilung der Leitfahigkeit der Atmos- 
phiire iiber dem grossen Ocean nach den Beobacht- 
ungen der Galilee,’’ A. Nippoldt. 
‘<Determination of the Pole Distance of a very 
Small Magnet’’ (abstract), J. M. Miller. 
