138 
the coalescence of vesicles averaging from 4 to 4 inch in diame- 
ter. These cavities were often lined with a white crystalline 
crust, and generally contained white crystalline pellets, each 
about one-third the size of the cavity in which it occurred. 
Minute crystals of specular iron were detected upon the surfaces 
of these pellets. The glassy part of the rock, which still re- 
mains clear, contains trichites and globulites similar to those 
in the unaltered obsidian, but they are more numerous in the 
artificially-altered rock. 
The vesicular glassy basalt lava of Kilauea, when examined 
under the microscope, is seen to contain crystals of olivine and 
minute crystallites which have not hitherto been referred to any 
particular mineral species. A specimen of this lava, kept for 
960 hours at a temperature ranging from 750° to 1200° C., 
shows that the olivine crystals have undergone no appreciable 
alteration, but the glass itself has become perfectly opaque and 
black, owing to the separation of magnetite. 
The specimens of basalt from the Giant’s Causeway were 
fused in Stourbridge crucibles in a gas furnace. One, which 
was cooled rapidly, appears under the microscope as a clear 
glass containing vesicles ; another, cooled slowly, is black and 
opaque, except in certain spots where a prismatic structure is 
visible, the marginal portions of the prisms having a radiating 
crystalline or fibrous character. 
In another case some of the powdered basalt was again fused, 
and a fragment of cold basalt was placed on the surface and 
allowed to sink into the molten mass. The result was a glass, 
which, under the microscope, appears perfectly clear except in 
the immediate vicinity of the immersed fragment, which is 
surrounded by an opaque black border containing divergent 
groups of colourless transparent or translucen* crystals. The 
. black border, where it joins the clear glass, is sharply defined, 
and its opacity and blackness must be regarded as due to a 
separation of magnetite, asin the case of the altered Kilauea 
lava. 
The first series of experiments were made by Mr. Herman. 
The specimens from the Giant’s Causeway were experimented 
upon by Mr. Rodwell. 
Zoological Society, June 1.—Dr. A. Giinther, F.R.S., 
Vice-President, in the chair.—Dr. A. Giinther, F.R.S., ex- 
hibited and made remarks on a specimen of a small fish of the 
genus /ierasfer embedded in a pearl oyster.—The Secretary 
made some remarks on the most interesting objects he had ob- 
served during a recent visit to the Zoological Gardens of 
Rotterdam, Amsterdam, Cologne, Antwerp, and Ghent.— 
A leiter was read from Mr. J. M. Cornely, of Tours, C.M.Z.S., 
stating that his pair of Michie’s Deer had bred in his park, and 
that a young one had been born on May 15.—Mr. Beddard read 
notes on the convoluted trachea of a Curassow (Nothocrax 
wrumutum), and on the form of the syrinx in certain Storks. — 
Mr. W. F. Kirby read a paper containing an account of a small 
collection of Dragon-flies which had been formed by Major]. W. 
Yerbury at Murree and Campbellpore, N.W. India. The col- 
lection contained examples of about twenty species. 
Physical Society, May 22.—Prof. Balfour Stewart, Presi- 
dent, in the chair.—Messrs. C. A. Bell, W. C. Johnson, and 
James Swinburne were elected Members of the Society.—The 
following communications were read:—On the sympathetic 
vibrations of jets, by Mr. Chichester A. Bell. It has been 
assumed hitherto that a gaseous or liquid jet vibrates under the 
influence of a limited range of tones only ; effective tones being 
those which do not differ greatly in pitch from the normal 
or proper tone of the jet, discovered by Savart and Sondhauss. 
The author has found, however, that, when the pressure under 
which a jet escapes is not too great, the latter is affected by all 
tones lower than the normal, as well as by some above it. 
Changes may be excited in a jet of either kind by vibratory 
motions of the jet orifice, or of the fluid behind or external to 
the orifice. These changes take the form of slight swellings 
and contractions, which become more pronounced as the fluid 
travels away from the orifice, and finally cause the jet to break 
or become discontinuous at a distance which depends upon the 
intensity of the initial disturbances. At any point within the 
continuous portion of the jet the successive swellings and expan- 
sions represent both the form and the relative intensities of 
vibrations impres ed upon the orifice, and the jet is therefore 
capable of reproducing very complex sounds, such as those of 
speech and music. A vibrating jet of air does not, however, 
emit sound when it plays into free air, or into the wide end of a 
NATURE 
[ Fune 10, 1886 
tube communicating with the ear; but when it plays against a 
very sail orifice in the end of a hearing tube, loud sounds may 
result. This reproduction is most intense when the hearing 
orifice is placed in the axis of the jet, just within the breaking 
point, but becomes gradually feebler as the hearing orifice is 
moved towards the jet orifice or out of the line of its axis. 
Beyond the breaking point the sounds from the jet at first become 
confused, and finally are lost. A jet of gas, like a liquid jet, 
only vibrates so as to produce its normal tone when it strikes 
upon some obstacle which serves to diffuse the disturbances due 
to impact, or throw them back upon the orifice. The vibrations 
of an air jet are also loudly reproduced as sound when it is 
directed against a small flame below the apex of the blue zone. 
Liquid jets are but slightly sensitive to aérial sound-impulses, 
but become highly sen-itive when the jet tube is rigidly attached 
to a sound-board. The vibrations of a jet so mounted are best 
perceived as sound when the stream strikes upon a rubber mem- 
brane tied over the end of a narrow tube which communicates 
with the ear. For accurate reproduction of speech and sounds 
in general the jets should be at such a pressure as to respond 
visibly to a note of about 4009 vibrations per second ; and the 
membrane should be at such a distance from the orifice that the 
jet never breaks or becomes discontinuous above its surface. The 
vibrations of very fine jets of any conducting liquid become 
loudly audible when a portion of the jet, or the ‘‘nappe” 
formed when it strikes upon a flat surface, is included in 
circuit with a battery and a telephone. This may be accom- 
plished by letting the jet impirge on the end of an ebonite rod, 
through the centre of which passes a platinum wire ; the upper 
end of the rod is surrounded by a short tube or ring of platinum, 
the upper margin of which forms a continuous, slightly convex 
surface with the exposed end of the central wire and the ebonite. 
The wire and ring form: the terminals of the circuit which is 
completed through the ‘‘nappe.” Distilled water containing 
1/300 of its volume of pure sulphuric acid is recommended as 
the jet liquid. The author advances a new theory to account 
for the growth of the vibratory changes in liquid and gaseous 
jets. —On some thermo-dynamical relations, part 5, by Prof. 
W. Ramsay and Dr. S. Young. In parts 1 and 2 of this series 
of papers it was shown that the ratio of the absolute tempera- 
tures of any two bodies corresponding toa given vapour-pressure 
bears a simple relation to the ratio at any other pressure, which 
may be expressed by the equation A’ = & + c(t’ — 7); where 
A’ and & are the two ratios, ¢ is a constant, and <’ and fare the 
temperatures of one of the two bodies. The determination by 
Schumann (Pogy. Ann., N.F. 12, 46) of the vapours of methyl- 
formate and twenty-seven homologous ethers made it possible 
to compare the vapour-pressures of a large number of bodies be- 
longing to the same class. It was found that when the ethers 
were compared with ethyl acetate, which was taken as the 
standard, in every case c = 0, and therefore A’ = 2. The 
temperatures corresponding to the three pressures 269, 760, and 
1300 mm. are given by Schumann. Taking the niean value of 
& for those pressures as correct, and recalculating the tempera- 
tures, the greatest difference between the found and recalculated 
temperatures is 0°°7 C. ‘The vapour-pressures of water or any 
one of the ethers being accurat ly known, it is sufficient to 
determine the boiling-point of any ether belonging to this class, 
in order to construct its vapour-pressure curve. The absolute 
temperatures corresponding to the pressures 200 and 1300 mm. 
for any ether are *89795¢ and 1:0488/, where ¢ is the boiling- 
point at normal pressure in absolute temperature. —A grid-iron 
slide-rule by Mr. Stanley, designed by Mr. Thacher, was 
explained by Mr. C. V. Boys. It was equivalent to a slide 
60 feet long, and performed multiplication and division with an 
error not exceeding the 1/40,000 part.—Specimens of safety 
explosives and their results in shattering blocks of lead were 
exhibited by H. Sprengel. 
Geological Society, May 12.—Prof. J. W. Judd, F.R.S., 
President, in the chair.—Matthew Blair was elected a Fellow, 
and Prof. H. Rosenbusch, of Heidelberg, a Foreign Corre- 
spondent of the Society.—The following communications were 
read :—On the maxilla of Iguanodon, by J. W. Hulke, F.R.S. 
—Notes on the distribution of the Ostracoda of the Carboni- 
ferous formations of the British Isles, by Prof. T. Rupert Jones, 
F.R.S., and J. W. Kirkby. Although all the Ostracoda of the 
Carboniferous formations are not yet described, there are 170 
species and notable varieties known, belonging to thirty-three 
genera of nine families. About twenty-five of these species, not 
yet described, but determined by the authors, are introduced into 
