58 
NATURE 
[May 20, 1886 
in the case of Bacteria and other minute m‘cro-organ- 
isms. 
As representing this last-named science we may spe- 
cially mention a magnificent collection of the photographs 
of sun, stars, and planets which have recently astonished 
and delighted astronomers. The collection included speci- 
mens of the results recently obtained by Dr. Janssen, the 
Brothers Henry, Mr. Common, and Dr. Gill. Among 
these the star-photographs by the Brothers Henry,a photo- 
graph of a sunspot by Dr. Janssen, in which the minute 
structure of the penumbra and bridges of a large sunspot 
were exquisitely slown on a scale of something like 
10 feet to the solar diameter, and two exquisite photo- 
graphs of Saturn, enlarged eleven times by the Brothers 
Henry, excited the greatest wonder. 
The Solar Physics Committee sent a collection of the 
daily solar photographs which they are now obtaining 
from India and the Mauritius to supplement the Green- 
wich series. These photographs are on scales of 12 
inches or 8 inches to the solar diameter. 
Mr. Norman Lockyer exhibited some photographs of 
spot spectra showing the widening of the lines and the 
reversal of H and K; and also some photographs illus- 
trating the first results of a new branch of work recently 
undertaken at South Kensington, in which it is hoped 
eventually to obtain photographs of the spectrum of the 
chromosphere and prominences without an eclipse. The 
photographs showed that the bright lines H and K have 
already been caught. Mr. Lockyer also exhibited the 
new split-grating spectroscope recently described at the 
Royal Society; the green line of thallium or the red 
line of lithium being shown between the D lines. 
Nor must we forget to mention a selection of drawings 
of the sun on a large scale from those now daily made 
at Stonyhurst College Observatory ; these were exhibited 
by the Rev. S. J. Perry. Special care has been devoted to 
the facula, which are drawn with a red pencil, and their 
position is as accurately determined as that of the spots. 
Mr. Howard Grubb exhibited a model of an equatorial 
and observatory which he has proposed for the 3-feet 
refractor for the Lick Observatory. All the required mo- 
tions of the telescope, dome, and rising floor are effected 
by water-power (represented here by clockwork) governed 
by an electrical arrangement, the commutator being port- 
able and carried by observer. By this arrangement the 
necessity of assistants, even in case of the largest sized 
instrument, is obviated, and the observer himself can, 
from any part of the Observatory, control all the motions 
of instrument and dome without using any physical 
exertion. 
Even observatory clocks were not neglected. Dr. 
Leonard Waldo, of Yale College, U.S., exhibited a gravity 
escapement adapted for use in a precision clock, in which 
the escapement lifts the gravity arms with a gradually- | 
increasing velocity, and with more certainty than in the 
ordinary forms ; and a new astronomical clock. 
Finally the Eclipse Committee of the Royal Society were 
represented by charts of the West Indies and of the Island 
of Grenada, showing the path of the total eclipse of 
August next, arrangements to observe which are now 
being made. 
In pure physics the fzéce de résistance was the colour 
photometer, for comparing the luminosity of colours 
and for testing the perception of colour, exhibited 
by Capt. W. de W. Abney, and Major-General Festing. 
The form exhibited was an improvement upon the original 
one, which was fully described-in NATURE a little time 
ago. 
Two exhibits by Mr. A. Stroh, also optical, may 
next be referred to. The first was an apparatus for show- 
ing stereoscopic effects on a screen; the next was an 
instrument for enlarging the angular division by means 
of reflectors, and thereby causing an object to be seen in 
exaggerated relief. 
Electrical science was represented by the following 
new electrical apparatus, exhibited by the Electrical 
Power Storage Company: (1) various types of cells; 
(2) ring contact switches; (3) automatic switch, for 
closing the circuit when the dynamo is running at the 
required speed, and for breaking it in case of accident ; 
(4) hydrometers, specially for use withthe Company’s cells ; 
(5) pocket voltmeter for cell-testing ; (6) automatic switch 
to cut out two or more cells when dynamo is started 
to keep constant electromotive force on lamps. 
In addition to these there were the following, contri- 
buted by Messrs. Woodhouse and Rawson :— 
(1) Assortment of incandescent lamps, showing the 
latest developments in connection with the manufacture 
of incandescent lamps. (2) Small arc lamp, giving 200 
to 300 c.p. or more if required: specially designed for 
being connected upon the same circuit with incandescent 
lamps of ordinary c.p., and being run by the same 
dynamo. These lamps can be also wound for running 
in series. (3) Switch-boards, illustrating the universal 
system introduced by Messrs. Woodhouse and Rawson. 
(4) Electric-lighting switches and safety-junctions, for 
manipulating currents of from 200 to 500 amperes and 
upwards. 
Mr. Pitkin exhibited some very interesting portable 
electric lamps intended for use in coal-mines and powder- 
magazines. A small teak box contains three or more 
accumulator-cells, which, when charged, give a continuous 
light for ten hours. In a modified form of the invention 
the lamp is detached from the box containing the accu- 
mulators, and is electrically connected to it by means 
of a flexible cord; by this arrangement a very’ con- 
venient railway reading lamp is formed, as the box 
can be placed under the seat or on the rack, and the 
lamp itself either held in the hand, or hooked to the back 
cushions or to the button-hole of the coat of the reader 
in a convenient manner. 
A new electrical influence-machine, having eight disks 
working within a glass case, was exhibited by Mr. 
Wimshurst. 
Electricity applied to meteorology was represented by an 
electrical wind-vane and indicator exhibited by Mr. F. M. 
Rogers. This instrument enables the direction of the wind 
to be ascertained at any moment, and at any reasonable dis- 
tance from the vane, within a house, observatory, or office. 
One vane will actuate several receivers, which are quite 
independent of each other. Should the vane remain for 
many hours upon any one point no waste of current 
takes place ; the expenditure of such being limited to the 
momentary impulse required to effect change of direction 
upon the dial of receiver. 
Messrs. de la Rue and Hugo Miller showed how the 
chloride of silver battery could be applied to electric 
lighting by a quantity arrangement. Instead of using a 
solution of chloride of ammonium simply, the solution, 
containing 24 per cent. salt, is converted into a vegetable 
jelly, by dissolving in it Ceylon moss (Agar-Agar) to 
make a stiff jelly ; this supports the zinc plate. The 
chloride of, silver in powder is spread evenly on the 
bottom of the dish on which a piece of silver foil is 
placed. 
One of the most interesting exhibits was by Mr. Conrad 
Cooke, C.E., who showed Dr. Auer von Weisegg’s in- 
candescence system of burning gas. A small Bunsen 
flame burning about 23 feet of gas per hour gave a 
dazzling light of about twenty candles by suspending in 
it a gauze cylinder which had been impregnated with the 
salt of a rare earth (probably zirconium). Tested by the 
spectroscope, the light showed a large excess of blue rays 
as compared with an ordinary gas: flame. 
Voltaic cells with solid electrolytes were exhibited by 
Mr. Shelford Bidwell. 
Great excitement was caused among the chemists by 
the specimens of the new element germanium and some 
