324 
NA TORE 
[ Feb. 1, 1883 
the machinery and elements is a little less than 250 kilogrammes. 
The real effect on the air can only be found by experiments in 
the air, but according to measurements taken with a dynamo- 
meter of the horizontal tendency to motion, it is about the same 
asin the experiment tried by Dupuy de Lome. The motive 
power of Dupuy de Lome having been obtained with eight men 
working his large screw, whose diameter was 9 metres, it may 
be inferred that the results in the present case will be more 
advantageous in the ratio of ‘wo and a half to one. These 
results are not very powerful when compared with the immense 
power of aérial currents. But MM. Tissandier have no intention 
of directing their balloon against strong winds. Their object is 
to organise an apparatus with which rational experiments may be 
made in the air, and they have taken advantage of the most 
recent improvements of science. If their elongated balloon 
answer their wishes, a real advance will be registered in the 
history of aéronautics. 
EXCAVATIONS are being carried out on Blackheath for the 
purpose of exposing the ‘‘deneholes” which have puzzled 
geologists and archzologists, and of which we gave some 
account in vol. xxiii. p. 365. 
In 1884 a general Italian exhibition will be opened at Turin. 
Among the exhibits will be works in mathematics, physics, and 
general chemistry. 
THE ‘‘ Treatise on Marine Surveying,” reviewed in last 
week’s NATURE, is published by Messrs. Macmillan and Co., 
and not by Mr. Murray. 
THE additions to the Zoological Society’s Gardens during the 
past week include a Mona Monkey (Cercopithecus mona @ ) from 
West Africa, presented by Mr. J. N. Flatau; a Crested Porcu- 
pine (Zystrix cristatus) from West Africa, presented by Mr. 
Joseph J. Doke ; two Pileated Jays (Cyanocorax pileatus) from 
La Plata, presented by Capt. Gamble; two Grey-breasted 
Parrakeets (Bolborhynchus monachus) from the Argentine Re- 
public, presented by Mr. Tomas Peacock ; an European Tree 
Frog (Hjla arborea), European, presented by Mrs. M. B. 
Manuel ; a Malbrouck Monkey (Cercopithecus cynosurus 6) from 
East Africa, a Macaque Monkey (M/acacus cynomoleus 2 ) from 
India, deposited ; a Water Chevrotain (Hyomoschus aquaticus), 
born in the Gardens. 
OUR ASTRONOMICAL COLUMN 
VARIABLE STARS.—The following are Greenwich times of 
heliocentric minima of Algol :— 
h. m. 
eb is 20s mee aan 
February 3, 8 47 | 
17, 16 52 March 12, 15 23 
- 20, 13 41 155) D2eoe 
23, 10 29 TSO) at 
The light-equation (geocentric—heliocentric) in seconds, may be 
found from the expre-sion— 
460°2s. R. sin (S+35° 28'-7), 
where R is the earth’s radius-vecto-, and S the longitude of the 
sun. S Cancri will be at a minimum about the following 
times :—February 2, at 9h. g4om. ; February 21, at Sh. 55m. ; 
and March 12, at 8h. 20. A minimum of U Cephei occurs on 
February 5, about 13h. 26m. x Cygni is at minimum on March 
17. This year’s maximum of Mira Ceti is not observable. 
According to the observations of Mr. Knott in 1881 and 1882, a 
maximum of T Cephei, when the star is about 6°5m., may be 
expected towards February 17 ; the position of this variable for 
1880 is in R.A. 2th. 7m. 57s , Decl. +68° o'"1; it is No. 3731 
in Felorenko’s catalogue from Lalande. 
RePorTeD DIsCOVERY OF A CoMET.—A Reuter’s telegram 
from Puebla, Mexico, January 23, states that a comet had been 
discovered there near the planet Jupiter, of which no further 
account has been received at the time we write, nor has a some- 
what hurried examination of the vicinity between clouds revealed 
anything brighter or more cometary in aspect than our very old 
friend, the first nebula of Messier’s catalogue near ¢ Tauri, 
which has proved ‘‘a mare’s nest” for more than one incipient 
comet-hunter. Jupiter was close at hand on January 22, but 
there was a full moon on that date, which hardly favours the 
suggested explanation. Messier 1, it may be remembered, led 
to more than a single false alarm when observers were on the 
look out for Halley’s comet in 1835. 
THE NEXT RETURN OF D’ARREsT’s COMET.—At the sitting 
of the Paris Academy of Sciences on January 22, M. Leveau 
communicated elements of the orbit of D’Arrest’s comet of short 
period, for the approaching return to perihelion. He states 
that on account of the great perturbativns suffered by the comet 
from its passage near Jupiter during the period 1859-1863 (in 
April, 1861, it passed within 0°36 of the earth’s mean distance 
from the planet), and the want of observations at its third 
appearance in 1864, it has not been possible to combine in the 
same system of elements the observations made in 1851 and 
1857 with those of 1870 and 1877. He has consequently been 
obliged to determine the osculating orbit in 1883, from the 
elements which best represent the observations of 1870 and 
1877 alone. The following are the elements of the comet’s 
orbit for 1883, June 12°0, M.T. at Paris :— 
Mean anomaly ... ... 206 328 13 20°3 
Longitude of perihelio 319 If 10°S8) Mean 
> ascending node 146 7 210 > equinox 
Inclination’ <=") 2) =e 15 41 471) 1880°0 
Angle of eccentricity 38 46 3374 
Mean daily sidereal motion 530765245 
It is M. Leveau’s intention to prepare and circulate among 
astronomers an ephemeris for what appears to be the most likely 
period during which to obtain observations, or from April 23 to 
November 25 in the present year, but from the comet’s great 
distance or unfavourable position it is probable that only the 
largest telescopes wil command it. By the above elements the 
comet will not arrive at perihelion until 1884, January 13°5765 
Greenwich M.T. 
MERIDIAN OBSERVATIONS OF NEBUL#.—Dr. Engelmann 
publishes the positions of about 120 nebulz, determined with 
the 6-inch meridian circle of the Leipsic Observatory, and re- 
duced to the beginning of the year 1870, with the mean epoch 
of observation and the annual precessions, thus aiding by meri- 
dian observations the extension of our knowledge of accurate 
places of these bodies, which has engaged the attention of 
d’Arrest, Vogel, Schonfeld, Schultz, and others, with equatorial 
instruments. Waluable material is thus being collected for the 
investigation of proper motiun amongst the nebula, which for 
want of reliable positions in past times, is not practicable at 
present, except perhaps in a few isolated cases. 
ERRATUM.—In last week’s ‘* Astronomical Column,” p. 300, 
lines seven and six from bottom, tor Washington read Wash- 
burn. 
PHYSICAL NOTES 
A DOUBLE-ACTION mercury air-pump, invented by Signor 
Serravalle, who was awarded a gold medal for it at a recent 
exhibition in Messina, is described in the Aiwista Scientifico- 
Industriale (Nos. 21-22). By a simple mechanical method 
two similar vessels are raised and lowered alternately with each 
other on opposite sides of a vertical support. A long caoutcho.2 
tube connecting their bottoms lets mercury pass from one to tlie 
other. - Each has at top a three-way cock ; one port of which in 
a certain position leads into a small open vessel to receive any 
excess of mercury, and another is connected by means of a 
caoutchouc tube with a spherical piece fixed laterally about the 
middle of the vertical support. This piece has three passages, 
communicating together ; two of them are opposite each other, 
and lead into the tubes from the mercury vessels; the other is 
connected by tubing to the vessel to be exhausted of air. The 
three-way cocks at the tops of the vessels are mechanically shifted 
at the top and bottom of their course by means of a toothed 
sector and rack in the one case, and a pin and projecting piece 
in the other. 
To observe directly the action of gravity on gases, M. 
Kraievitsch, of the Russian Chemical Society (Your. de Phys., 
