FEBRUARY 8, 1884. | 
stratum of clay, at the bottom of which the remains 
of wood were found. This blue earthy mineral has 
been identified as vivianite by Professor Clarke. 
Mr. Hillebrand, in the laboratory at Denver, has 
been examining the Leadville porphyries with respect 
to the proportion of precious metals contained in 
them. He has prepared a new gravity-solution, the 
borotungstate of cadmium, designed to replace in 
part the Thoulet solution, which is in some cases in- 
applicable in the separation of the mineral constitu- 
ents of rocks. He has also made various qualitative 
examinations of several minerals new to the west, — 
tantalates, columbates, and phosphates of rare earths. 
Dr. Mellville and Mr. G. F. Becker, at San Fran- 
cisco, have been investigating some of the chemical 
relations of quicksilver. 
In the laboratory at New Haven, Dr. William Hal- 
lock, at the suggestion of Mr. Arnold Hague, has 
begun a series of experiments upon the artificial pro- 
duction of geysers. Small models have been made 
that worked admirably with regular periods. An ar- 
tificial geyser, with a reservoir twenty-five feet deep, 
has been constructed, and will soon be in working- 
order. ‘The study of this model will be of exceeding 
interest. 
Topographical notes. — It was hoped that topo- 
graphical work could be carried on through the win- 
ter in Massachusetts; but owing to the continued 
bad weather through December, especially in the lat- 
ter part of the month, the work was greatly delayed; 
and about the middle of the month it was decided to 
postpone further field-work in the state until spring. 
Mr. Willard D. Johnson, assistant topographer, 
who has been preparing several small local maps 
in the Mono basin, California, has completed a map 
of the Parker-creek moraines, and began one of 
the Leevining-creek moraines. He has been unable 
to complete the latter on account of unfavorable 
weather. The map of the Parker creek moraines 
includes an area of about seventeen square miles, on 
a scale of four inches to the mile. The general map 
of the Mono basin covers some two thousand square 
miles, and the field sheets of the map are upon an 
approximate scale of one inch to one and three quar- 
ters miles. Several points of the transcontinental 
triangulation of the coast and geodetic survey are 
included. They give it scale and position. ‘The ver- 
tical relief is derived mainly from angles, and a line 
of levels connects the work with a determined point 
on the Carson and Colorado railroad. The map ex- 
hibits the outline of the ancient expansion of Mono 
Lake; the outlines of the ancient ice-stream of the 
adjacent Sierras with their present remnants. Agri- 
cultural and grazing lands are shown, and the areas 
of timber lines also indicated. 
Mr. J. D. Hoffmann, in the division of the Pacific, 
was busy during December, carrying on the detailed 
survey of the new Idria quicksilver district in Cali- 
fornia. 
Prof. A. H. Thompson, geographer, was occupied 
during December in the determination of the latitude 
and longitude of Fort Wingate, New Mexico, which 
work has been satisfactorily completed. 
SCIENCE. 
167 
PUBLIC AND PRIVATE INSTITUTIONS. 
Harvard college observatory. 
Funds. — In his report to the president of the uni- 
versity, the director of the observatory states that 
the annual subscription of five thousand dollars, 
which has been in force for five years, has expired 
by limitation, and that an attempt to raise a fund of 
one hundred thousand is meeting with good success, 
about half having been already obtained. _ 
Variable stars. — The study of the variable stars has 
been continued by Mr. Chandler. The bibliography is 
nearly completed, so far as the first extraction of ref- 
erences is concerned. Notes have been prepared to 
exhibit the evidence of variability which has been 
published with regard to about twelve hundred stars. 
This list excludes many cases in which the evidence is 
entirely inadequate. A table, giving all the published 
maxima and minima of each of the variables of long 
period, is now in process of construction. The prep- 
aration of this table has led to the important result 
that an interval of several years occurs in which no 
observations appear to have been made of about thirty 
of these objects. About one hundred and forty stars 
belong to this class; and, since last April, all of them 
have been observed by Mr. Chandler with the six- 
inch Clacey equatorial mounted in the west dome. 
Charts of the vicinity of these variables have been 
prepared, and some progress made towards their com- 
pletion. Similar charts have been made for about 
seventy telescopic stars suspected of variability, and 
nearly two hundred observations of these stars have 
been obtained. The color of the variable stars is also 
estimated, about three hundred observations of this 
class having-already been made. The circular distrib- 
buted, asking the aid of amateurs and others, in 
the observation of stars known or suspected to be 
variable, has, it is believed, secured much valuable 
co-operation. Numerous replies have been received, 
and important results have been obtained, espe- 
cially by Mr. H. M. Parkhurst of New York, and by 
the Rev. J. Hagen, S8.J., of Prairie du Chien, Wis. 
The great difficulty encountered by most of the ob- 
servers was that of identifying with certainty the 
fainter stars, although this is one of the first things 
that should be learned by any person desiring to do 
useful astronomical work. 
Astronomical photography. — With the assistance 
of Mr. W. H. Pickering, an investigation was under- 
taken in astronomical photography. Two objects 
were kept in view, —first, the determination of the 
light and color of the brighter stars; and, secondly, 
the construction of a photographic map of the whole 
heavens. After numerous preliminary observations, 
a method was employed by which a photograph of 
the brighter stars included in about one-twelfth of 
the entire heavens could be obtained on a single 
plate. Maps were also obtained, containing a region 
of about fifteen degrees square, containing stars as 
faint as the eighth magnitude. The color exercised 
a marked influence on the intensity of the photo- 
graphic images, in some cases producing a difference 
equivalent to four magnitudes. It is thought that 
