490 
these changes, so written that many, if not all, the causes can 
be traced in the curves which they produce. Various tables and 
diagrams are appended to the paper. 
CoLoneL GILDER has started from Winnipeg on his expedi- 
tion to the Arctic regions, with the object of reaching the North 
Pole. 
THE deaths are announced of M. Paul Soleillet, the explorer 
of Shoa in North-East Africa, and of Herr Robert Flegel, the 
explorer of the Niger and Binue. 
TuE celebrated traveller and botanist, Dr. Schweinfurth, 
lectured recently at Berlin on the Kew Botanical Gardens, which 
he characterised as the finest in the world. Kew, he said, is 
the Botanical Foreign Office for all nations, for it is the centre 
of all botanical news from all parts of the world. 
WE have received ‘‘ An Account of the Progress of Astro- 
nomy in the Year 1885,” compiled for the Smithsonian Institu- 
tion by Prof. W. C. Winlock. The investigations reviewed 
comprise (among others) Prof. Pritchard’s photometric researches 
as consigned in the Oxford ‘* Uranometria,” M. Duner’s cata- 
logue of stellar spectra of the third type, Drs. Gill and Elkin’s 
determination of southern star-parallaxes, Prof. Bakhuysen’s of 
the rotation-period of Mars, Prof. de Ball’s of the nutation con- 
stant, Prof. Peters’ of the orbit of 61 Cygni, and Prof. Langley’s 
inquiries into the temperature of the moon’s surface. M. Faye’s 
theory of the origin of the solar system, with Prof. G. H. 
Darwin’s criticisms upon it in NATURE, are prominently dealt 
with. We hear with pleasure of the progress towards com- 
pletion of Prof. Rowland’s photographic map of the normal 
solar spectrum. The amount of detail contained in it may be 
judged of from the one fact that 120 lines are visible between 
H and K, the original negatives showing 150. The most striking 
astronomical events of the year, z.e. the outburst of new stars in 
Andromeda and Orion, the photographic discovery of a nebula 
in the Pleiades, and the meteoric shower of November 27, are 
chronicled in due and interesting detail. Seven comets were 
observed in 1885, of which five were seen for the first time, the 
others being expected returns of Encke’s and Tuttle’s. Nine 
minor planets were discovered. The Report concludes with a 
useful bibliography of astronomical works published in 1885. 
In March, 1884, Prof. Holden offered to observe at the 
Washburn Observatory the 303 fundamental stars for the 
southern zones of the ‘‘ Astronomische Gesellschaft.” The offer 
was accepted ; the work was begun May 2, 1884, and finished 
December 25, 1885. The results are contained in vol. iv. of the 
‘* Publications of the Washburn Observatory,” now before us. 
When Prof. Holden was appointed to the Lick Observatory in 
October 1885, 468 observations were still wanting to complete 
the series. These were very creditably supplied, before the end 
of the year, by his assistants, Mr. Updegraff and Miss Lamb. 
In all, 6444 observations were made with the Repsold meridian- 
circle ; each star of the 303 was completely observed six times ; 
and instrumental constants were determined for each night. No 
pains were spared to secure accuracy. The probable error of a 
single bisection of Polaris was estimated at not above 0’'1 for 
poor seeing, and 0”*o5 under the most favourable conditions. A 
list of corrections to standard star-catalogues (p. 69) forms a 
valuable addition to the contents of the volume. 
WE have to acknowledge the receipt of the Calendars for the 
Session 1886-87 of the University Colleges of Dundee and 
Bristol, and of the Durham College of Science of Newcastle-on- 
Tyne. 
THOsE interested in natural history will be glad to hear that 
Mr. Quaritch issues this week vol. iii. (the ‘‘ Quadrupeds”’) 
of the Memorial Edition of ‘* Bewick’s Works,” which he is 
publishing—to be complete in five volumes. 
NATURE 
[Sepd. 16, 1886 
THE additions to the Zoological Society’s Gardens during the © 
past week include a Spring-bok (Gazella euchore &) from South — 
Africa, presented by Capt. John Hewat, C.M.Z.S. ; two Tala-— 
poin Monkeys (Cercopithecus talapoin) from West Africa, pre- — 
sented by Mr. R. E. Dennett; two Red-headed Finches 
(Amadina erythrocephala 8 2) from South Africa, two Sation | 
Finches (Sycalis faveola $ §) from Brazil, presented by Mr. H, 
B. James ; a Leadbeater’s Cockatoo (Cacutua leadbeateri) from 
Australia, presented by Mr. J. Davis; a Roseate Cockatoo 
(Cacatua roseicapilla) from Australia, presented by Mr. G. H. 
Hawtayne, C.M.Z.S.; a Herring Gull (Larus argentatus), 
British, presented by Mr. E, Penton, jun., F.Z.S.; a West 
African Python (Python sebe) from West Africa, presented by | 
Major A. Morton Festing ; a Smooth Snake (Coronella levis) 
from Hampshire, presented by Mr. W. H. B. Pain ; a Leonine 
Monkey (Jacacus leoninus §) from Arracan, deposited; two 
Crested Pigeons (Ocyphaps lophotes), a Geoffroy’s Dove (Peristera 
geoffroti), bred in the Gardens. 
OUR ASTRONOMICAL COLUMN 
THE INNER SATELLITES OF SATURN,—Writing in the — 
5 
a 
Astronomische Nachrichten, Nos 2743, Prof. Asaph Hall states” 
that he has now finished the reduction and discussion of th 
observations of Titan and the five inner satellites of Saturn made 
at Washington since the mounting of the 26-inch refractor in 
1873. These observations have been made with the filar micro- 
meter, and most of them are observed angles of position and 
distances. The average probable error of a single observation 
for the position of a satellite is +0’'27. A remarkable result 
of the discussion is that the Washington observations of the five 
inner satellites can be satisfied within the limits of their probable 
errors by circular orbits. At the beginning of this discussion 
Prof. Hall hoped that the observations would determine the 
positions of the lines of apsides with such accuracy that the 
motions of these lines would be known, and that thus we might 
obtain data for a new determination of the mass of the Ring, 
and of the figure of the planet. But the resulting circular orbits 
for the inner satellites make the position of a line of apsides in- 
determinate, and for the present the mass of the Ring remains 
unknown. 
On account of the difficulty of making good micrometrical 
measurements of the inner satellites of Saturn, astronomers have 
revived the old method of observing their conjunctions with the 
ends of the Ring, or with some other marked feature in the 
Saturnian system. A series of observations of conjunctions with 
the ends of the Ring was made at Toulouse in 1876 and 1877 
by MM. Tisserand and Perrotin ; and in order to test the old 
method of observing, Prof. Hall has compared these measures 
with his elements of the five inner satellites. The result at 
which he arrives is that the probable errors of a single residual 
are larger for the Toulouse observations (= -£ o’"41 in the mean) 
than in the micrometrical measurements at Washington. Prof. 
Hall therefore concludes that observations of these satellites with 
filar micrometers are among the best we have, and since they 
are definite measurements, and are made in very different posi- 
tions, a result deduced from them is more likely to be free from 
constant errors. He suggests that probably the best way to 
effect an improvement in such measurements is to devise some 
new arrangement of the wires of the filar micrometer. 
THE INVENTION OF THE SEXTANT.—Dr. J. L. E. Dreyer 
points out, in the Astronomische Nachrichten, No. 2739, an 
historical error which has crept into several astronomical works, 
although it was refuted some fifty years ago by Prof. Rigaud in 
a series of papers communicated to the Waztical Magazine. In 
the books referred to, it is stated that the principle of the con- 
struction of the sextant was communicated to John Hadley by 
his brother, a Capt. Hadley, who had in his possession a sextant 
given to him by Capt. Godfrey, brother of Thomas Godfrey, ©} 
Philadelphia, the real inventor of the instrument. But it appears 
there never was such a Capt. Hadley. The brothers of John 
Hadley were—one a barrister, the other a physician; and he 
himself was not an instrument-maker by profession (as has been 
asserted), but, as an amateur, occupied himself with mechanical 
pursuits, and was the first to bring the polishing of reflecting 
telescopes to any perfection. On May 13, 1731, John Hadley 
; 
