Jury 20, 1899] 
NATURE 
281 
Tue Pilot Chart of the North Atlantic Ocean for July, issued 
by the Hydrographic Office of Washington, contains an article 
on tropical cyclonic storms or West India hurricanes which 
are prevalent at this season of the year. Froma table showing 
the number of storms experienced between 1885 and 1898, it is 
seen that the greater number occur between August and October. 
The nature and mean path of the hurricanes are exhibited by a 
diagram. In its earlier stages, the centre of the path of the 
storm has a certain amount of westing, due to the general west- 
ward motion of the atmosphere in the low latitudes in which 
the storm originates, and the whirl is small, probably less than 
100 miles in diameter, but its growth is rapid, so that in the 
middle and higher latitudes it may attain a diameter of 500 or 
even 1000 miles. The velocity of progression along the track 
of the disturbance reaches from twenty to thirty miles an hour 
in high latitudes, while the velocity of the whirl itself, in a 
direction against the hands of a watch, attains the force of a 
hurricane. 
Tue interesting ani useful ‘‘Glossary of Popular Local and 
Old-fashioned Names of British Birds” contained in “* A 
Dictionary of Bird Notes,” by Mr. Charles Louis Hett, has 
been issued separately by Jackson, of Brigg. 
THE additions to the Zoological Society’s Gardens during the 
past week include a Bonnet Monkey (A/acacus sznicus, 8 ) from 
India, presented by Miss Nesta Bevan; a Black-faced Spider 
Monkey (Af¢e/es ater) from Eastern Peru, presented by Mrs. K. E. 
Mackenzie ; two Campbell’s Monkeys (Cercopithecus camp- 
Sellé, 6 9) from West Africa, presented by Captain F. R. B. 
‘Parmeter ; a Mozambique Monkey (Cercopithecus pygerythrus) 
from East Africa, an Arabian Gazelle (Gazella arabica) from 
Arabia, presented by Mr. B. T. Ffinch; two Common Foxes 
{Canis vulpes) from Russia, presented by Mr. A. H. Britten ; 
an Arctic Fox (Canis /agopus) from Iceland, presented by Mr. 
M. Magnusson; five Common Hedgehogs(Z7znaceus europaeus), 
European, presented by Mr. Geo. Long; three Chipping 
Squirrels (Zwmzas striatus) from North America, presented by 
the Rev. A. E. Tollemache; a Common Peafowl (Pavo cres- 
¢atus, 3) from India, presented by Miss A. S. Heldmann ; two 
Climbing Anabas (Anadbas scandens) from India, presented by 
Mr. P. Barford ; two Rheas (Rhea americana, white var.) from 
Argentina, two Syrian Bulbuls (Pycvovzotus xanthopygos) from 
Syria, an European Pond Tortoise (Zzys orbiculare), European, 
deposited; two Rose-coloured Pastors (Pastor rvoseus), two 
indian Mynahs (Acridotheres ginginianus) from India, two 
Bamboo Partridges (Bambustcola thoracica) from Northern 
China, two Lunulated Honey-eaters (J/edithreptes lunulatus), 
two Pied Grallinas (Gallina australis), two Musky Lorikeets 
(Glossopsittacus concinnus) from Australia, purchased; a 
Japanese Deer (Cervus stka, 9), born in the Gardens. 
OUR ASTRONOMICAL COLUMN. 
TeMreL’s Comer 1899 c (1873 II.). 
phemerts for 12h. Paris Mean Time. 
1899. R.A. Decl. Br. 
oem. os. Aes i 
July 20 20 39 34°3 —18 4 26 3°570 
21 40 461 18 37 9 
22 Ate57-0) ... - 19) Loped! 
23 43) 1955... - 19 4319 3662 
24 AAL2tT ... , 20) 16822 
25 45 326 ... 20 49 38 
200 ee 40 44°0 ... 21 22 55 
27 «-. 20 47 554 —21 56 9 3698 
Hormes’ Comer 1899 d (1892 III.).—Prof. C. D. Perrine 
gives full details of his rediscovery of the comet in Asér. 
Fournal, No. 465. It was found with the 36-inch refractor, 
NO. 1551, VOL. 60] 
using a power of 270. It appeared as a round nebulous mass 
about 30” in diameter, with only a slight brightening at the 
centre. The conditions were good, the sky being very clear 
and the star images steady. The object was very faint, not 
brighter than 16 mag., and very difficult to observe, so that the 
probable error of observation of its place was larger than usual. 
DyNAMICAL THEORY OF NEBUL.—In No. 465 of the 
Astronomical Journal, Dr. E. J. Wilczynski gives an extended 
explanation of a dynamical theory of ring and spiral nebulz 
which he first brought forward in 1896 (As/70.-Phys. Journad, 
vol. iv. p. 97, 1896). He starts with the assumption that the 
primordial nebula exists either as an assemblage of meteorites 
or as a gaseous mass obeying the laws of hydrodynamics. Then, 
in some unexplained way, each particle is to describe a circular 
orbit about the common centre of gravity, at which point there 
may or may not be a condensation. Such an arrangement is 
not necessarily stable, the limit depending on the relative ratios 
of the masses and distances of the individual particles, and the 
ratio of the mass of the central controlling body to its distance 
from the swarm. If these conditions allow stability the body 
may condense to a star, single or double. If the system be 
unstable, however, then on applying Kepler’s third law to the 
revolving particles it is found that the inner members, owing to 
their greater angular velocity, constantly advance with respect 
to the outer ones, and after an interval the particles originally 
lying along a vadéus of the swarm will be drawn out into a 
spiral curve, as is actually the case in the bodies known as 
spiral nebulee. According to this view, the age of a nebula 
would be to some extent indicated by the zzber of tts corls, 
and the author gives an interesting suggestion that this might 
be investigated by a minute comparative examination of all 
photographs of spiral nebulee of different dates. The paper 
concludes by indicating the possibility of determining the /azw of 
rotation of these bodies by a combination of spectroscopic and 
photometric observations. 
THE NATAL OBSERVATORY.—The annual report of Mr. E. 
Nevil, Government Astronomer of the Natal Observatory at 
Durban, consists chiefly of the detailed meteorological observ- 
ations made at the institution. The staff consists of the director, 
one senior astronomical assistant, one junior astronomical as- 
sistant, and one meteorological assistant. The astronomical 
equipment includes an 8-inch Grubb equatorial refractor, a 
3-inch Troughton and Simms transit instrument, sidereal and 
mean time clocks, 3-inch portable equatorial refractor, and an 
automatic signal transmitter and recorder. Owing to a reduc- 
tion in the vote to the observatory, much of the work has had 
to be put aside. 
The system of time signals established over the Colony has 
been carried on without alteration, this being facilitated by the 
erection of new wires. Since the appointment of the astronomer 
in 1882 there has been no official residence, the computations, 
&ce., having been mostly made in the open air. 
This is at last to be remedied by the erection of a residence, 
all the fixtures, water supply, &c., however, being provided by 
the astronomer himself. 
TEMPERATURE CHANGES IN YERKES OBJECT-GLASS.— 
Prof. Barnard has several times made series of measures with 
the large telescope to find if the changes produced in the 
instrument by variations in temperature were of sufficient 
amount to necessitate their consideration in delicate invest- 
igations. During the last year observations have been made 
of the focus at temperatures varying from — 22° F. to +80° F., 
the range thus being 102° (Astr. Journal, No. 462). The 
means of the observations made on nineteen nights show a 
marked difference in the focus, and it was found that the 
object-glass shortened 0°26 inch more than the steel tube which 
carried it. Micrometric measures of the difference in declin- 
ation between the stars 4¢/us and Pezone of the Pleiades 
showed a decrease of nearly 0:2 (from 0”°676 during July- 
September to 0”"491 during January-February). 
From the result of these experiments Prof. Barnard thinks 
that for exact work, such as parallax, with a large glass in a 
variable climate, these minute changes ought to be deter- 
mined and taken into account. 
In addition to these visual observations, careful determin- 
ations of the changes in the colour-curve during wide extremes 
of temperature are being carried on by Prof. Frost and Mr. 
Ellerman. 
