FEBRUARY 15, 1884.] 
the latest, March, 1850. Vol. ili. is stated by 
the publishers to be i in press. 
Of the papers reprinted in these first two 
volumes, only two of the more important are 
of a purely mathematical character, and these 
treat of the properties and methods of compu- 
tation of infinite periodic series such as arise in 
many physical problems, which series were 
first sy ns employed and Ssplnied by 
Fourier in 1822. Fourier’s treatise ' is to-day 
the best introduction to a knowledge of this 
kind of analysis, besides being one of the most 
brilliant expositions, in any branch of science, 
in existence. With the exception of a single 
paper of 42 pages, upon a differential equation 
relating to the breaking of railway bridges under 
loads moving at high speeds, the remaining 
papers all come under the head of fluid motion 
in one way or another, and include extensive 
discussions of the fundamental dynamical equa- 
tions of motion of perfect fluids, of viscous 
fluids, and of elastic solids. ‘These discussions 
treat, among other subjects, the theory of oscil- 
latory waves, the equilibrium of the earth in a 
fluid state, the variation of the force of gravity 
on its surface, and the undulatory theory of 
light. 
The work of Professor Stokes in hydrody- 
namics is of special importance in correcting 
and rediscussing the results obtained by La- 
grange and Poisson, and in paving the way for 
the more modern developments of Helmholtz 
and Thomson in vortex motion, and of Max- 
well in electricity and magnetism. 
1 Analytical theory of heat. 
lated, with notes, by Alexander Freeman. 
By JosEPH FOURIER. Trans- 
Cambridge, 1878. 
SCIENCE. 
205 
But the papers of Stokes which are prob- 
ably of most interest to the mathematical phys- 
icist of to-day are those upon the undulatory 
theory of light, in which he has added essen- 
tially to our knowledge of the constitution of 
the luminiferous ether by showing how the 
phenomena of aberration may remain unaf- 
fected by the fixity or motion of the ether, as 
also by his investigation of the theory of dif- 
fraction, by which he has sought to decide 
whether the vibratory motion of a plane polar- 
ized ray lies in the plane of polarization or at 
right angles to it. 
By these investigations, and by others, 
among which may be noticed that of the col- 
ored rings of Newton, he has explained diffi- 
culties in Fresnel’s undulatory theory, and 
essentially improved it. 
The treatise of Verdet,! which is the most 
complete and important exposition of the un- 
dulatory theory yet written, gives a complete 
bibliography of this subject, extending to 
many hundred titles, from which the reader 
can correctly estimate the labors of Professor 
Stokes in this field. 
The lifelong labors of Professor Stokes 
have given an immense impulse to mathe- 
matico-physical research in England ; and the 
republication of these papers by the syndics 
of the Cambridge university press is a grace- 
ful and well-deserved tribute to the Nestor of 
the greatest mathematical school in the world. 
1 Legons d’optique physique par E. Verdet. Paris, tome. i., 
1869; tome ii., 1872. The following translation and revision to 
date is in process of publication: Vorlesungen uber die wellen- 
theorie des lichtes, von E. Verdet. MHerausg. von Dr. Karl 
Exner, Braunschweig. Bd.i. 1881. 
INTELLIGENCE FROM AMERICAN SCIENTIFIC STATIONS. 
GOVERNMENT ORGANIZATIONS. 
Geological survey. 
Geologic work in the South Atlantic district. — 
Owing to the as yet incomplete state of the topo- 
graphic work in the southern Appalachians, the sys- 
tematic geologic survey of that section has not yet 
been commenced. However, several geologic recon- 
naissances have been made, and considerable collec- 
tions of paleontologic material have been sent into 
the main office of the survey. During the season of 
1883 Prof. H. R. Geiger examined the geologic struc- 
ture of a considerable portion of Virginia and West 
Virginia. During the latter part of July he was in 
the eastern part of Virginia, but in August trans- 
ferred his field of work to Greenbrier county, W. Va., 
where he studied the formations that are exposed 
between the Greenbrier River and the Lewis Tun- 
nel, just east of Alleghany station, W. Va. A 
collection of Devonian fossils was made. In Sep- 
tember his work was carried into Alleghany county, 
Va., where a careful examination was made of the 
rocks so well shown there. The thickness, dip, etce., 
of the beds were obtained, and an excellent series of 
typical specimens secured. In October the field was 
extended northward to Rockingham county, but bad 
weather impeded the operations. Through Novem- 
ber a special study was made of the foldings in the 
limestones that lie between the Blue Ridge and North 
Mountain, and a careful comparative examination 
made of the limestones of Rockingham and Rock- 
bridge counties, Va. 
Professor Ira Sayles was assigned to the north- 
eastern part of Tennessee, and adjacent portions of 
Virginia and Kentucky. The early part of July was 
spent by him in the examination of the caves near 
