Vegetable oils.

Marine Animaloi's. Marine Animal oils.

Mineral oils.
None.

They may be differentiated from each other by fat and the oils from cocoa-nut and palm-nut body the weight multiplied by the square of the

defined as a change of position, and in many ses the velocity of this change is a matter of inference, so that the path and direction of motion ly receive our consideration. If velocity is taken to consideration we introduce the element of time, ce the velocity of a point is the distance which [or would be if the velocity was constant] passed er in whatever unit of time is used as a standard. e second is the usual standard. We can then y in uniform motion the space described in any ae is equal to the product of the velocity and the 16. When the velocity is not constant it can no ger be measured by the quotient of the space by time, since these quotients will be different for ferent periods, and in variable velocities we asure the velocity, at any instant, by the space ich would have been passed over in the succeedsecond had the velocity been rendered constant that instant. Angular velocity, which is used to apare the speeds of rotation of bodies around ir axes, can also be constant or variable; it is velocity, in a circular path, of a point which is a radial distance equal to unity from the axis of ation of any rotating body; or, if the axis does pass through the body, it is the velocity, in a ular path, of a point situated at a distance from axis equal to unity, and in an assumed line ing the axis and the body revolving around it. an always be obtained by dividing the curvilir velocity of any point in a rotating or revolvbody by its radial distance from the axis. quipped with these few fundamental concep

much matter. The fact is that mass means the
intensity of the force of gravity divided by the
velocity due to the force of gravity at the end of one
second, and is a constant ratio at all points on the
surface of the earth. The great convenience of
this ratio for the purposes of the mechanic will be
seen when we recollect that in dynamics the in-
tensity of a force is measured by the velocity
which it will produce in one second, and if we
multiply this ratio (which is the mass) by the
velocity which is observed, we have the intensity
of the acting force in pounds. This leads us at
once to the momentum of a body, which is the in-
tensity of a constant force which has been (or
should have been to produce the same velocity)
acting upon it for one second, it is equal to its mass
multiplied by its velocity, in feet per second. If a
moving body be brought to rest in one second, the
momentum is the intensity of the constant force
which must be exerted through a space equal to
one-half the velocity of the moving body. In
speaking of momentum, unity of time is always
assumed as one of the conditions; thus the weight
of a body equals its momentum when gravity is
the force acting upon it.

N

(To be continued)

SCIENTIFIC NEWS.

phosphor bronze sheet and anglepieces used in her construction, prior to having boats built on a larger scale. The results have been beyond the Company's expectation as regards rigidity, absence of vibration, and the speed obtained. The cost of phosphor bronze boats will not much exceed those made of steel, and the metal is not subject to corrosion, like iron or steel.

We learn that the first conversazione of the

session of the Royal Microscopical Society wil be given at King's College on Wednesdayl Dec. 7th, when the suite of rooms of the library will be placed at the disposal of the Society for the reception of the visitors, and the exhibition of objects and appliances of interest to microscopists. The following exhibits are promised:-By the President (Prof. Martin Duncan, F.R.S.), rare sponge spicules from deep-sea soundings; by C. Stewart (secretary), specimens of double-staining; by F. Crisp (secretary), the collection of microscopical appliances that have been brought before the Society during the past year, including microscope-stands, illuminating devices, microtomes, turn-tables, &c.; by J. W. Stephenson, Amphipleura pellucida mounted in solution of phosphorus in bisulphide of carbon; by Dr. John Anthony, Wenham's new microscope-stand; by Powell and Lealand, new formula 4th homogeneous

18, we have all that are necessary to the study the first of his series of Cantor lectures on immersion objective, and possibly a higher

the industrial uses of the calcium com

kinematics, this word being used in its most pounds, Mr. Bolas performed the rare experi-
ited sense. Statics, on the other hand, evades ment of isolating the metai from its fused
questions of motion, and in it we confine our-
es to the study of forces at rest. What force chloride, by means of an electric current obtained
ly is we will probably never know until we from a machine on Pacinotti's principle driven
n the ultimate nature of matter; we do know, by a small gas-motor. Although calcium is the
rever, that whatever tends to produce motion, most abundant metal in nature, it has such an
actually produces motions in bodies at affinity for oxygen, that it is rarely seen out-
or brings or tends to bring a moving body side the chemist's laboratory, and not often
rest, or to change the direction of a moving there, so difficult is it to reduce to, and keep in,
y, is called force. We measure force by the metallic state.
intensity, in pounds, and limit it by its
ction and point of application. In terrestrial
chanics, to which we limit ourselves in this paper,
vity is the force which attracts all bodies to the

face of the earth in a vertical line; if allowed ct upon a free body in a vacuum it will produce alocity of about 32 2ft. at the end of one second, ing which time the body will have fallen a ance of 16-1ft. In order to define the centre of vity of a body we will have to precede it by the nition of the statical moment of a force which he intensity of that force multiplied by its perdicular distance from the point around which ends to, or actually does produce motion. We now define the centre of gravity of a body as t point which, if supported, leaving the body e to rotate in any direction, would balance all moments of the forces of the molecules of the ly due to the force of gravity; the body would have any tendency to turn about this point, at ich the total force of gravity acting upon the y may be assumed to be concentrated. The 1-known theorems of the parallelogram and allelopipedon of forces form the basis for the

tical treatment of forces which has received an

rmous development both analytically and

phically.

Sir Wyville Thomson has resigned his post as professor of natural history at Edinburgh.

Mr. H. N. Moseley has been appointed to the
chair of anatomy, at Oxford, vacant by the
death of Prof. Rolleston.

With a view of commemorating the services
of Father Secchi to astronomy, a committee has
been formed at Reggio, to collect funds for the
erection of a refractor of 27in. clear aperture.
In a paper recently communicated to the
Royal Institution of Cornwall, Mr. J. H. Collins
gives reasons for believing that the country
southward and westward of the Bodmin granite
is composed of no fewer than four distinct rocks
of very different ages, not merely of two
kinds as indicated by the maps of the Geological
Survey.

the

power on the same formula; by Swift and Son, their radial traversing substage in action; by Watson and Son, Crossley's new microscope, the illumination passing through the trunnionbar and by three total reflexions upon obtained by the mere lateral swing of the mirror, all degrees of obliquity can thus be mirror-arm, the lamp remaining stationary; by T. Curties, foreign microscopes by Prazmowski and Zeiss, and miscellaneous objects. Exhibits are also expected from the following:-Drs. Beale (treasurer), Gray, Milar, Matthews, &c.; Messrs. Bennett, Déby, Fox, Glaisher, De Souza Guimaraens, Ingpen, Ridley, Ward, White, &c. The invitations have been limited to 1,000.

Biological science owes not a little, already, to the marine stations instituted of late years, at Naples and elsewhere, for study of sea-life. An encouraging report was given by M. Lacaze-Duthiers the other day in the Paris Academy of the Zoological Station, at Roscoff,

on the coast of Finisterre. The number of as against 27 last year; eight of these have who have worked there this year is 38, persons been foreigners. A large fish-pond has been added, and the aquarium and laboratories, which naval minister put a small vessel at the disposal are yet to be made, will be quite near it. The of M. Lacaze-Duthiers, for dredging excursions. The experimental works at the Channel tunnel A large number of live animals are sent inland are progressing satisfactorily, the boring aver- Banyuls-sur-mer, on the Mediterranean, has been aging 28ft. per day of twenty hours. Mr. J. D. chosen for the new winter station, which will te Brunton has recently completed a patent of a inaugurated in January next. The site is on a machine for excavating tunnels of the kind; promontory at the month of a round bay, and is but the real difficulty appears to be the ventila-said to be charming. The building (rectangular) tion. That might be overcome while the work is in progress; but by what means can a tunnel 20 miles long, be rendered safe for passengers in a train drawn by an engine belching out volumes of carbonic acid?

The Fontaine Engine-the locomotive with the drivers on the top-has been tried on the Pennsylvania railroad and has not given satisfaction, apparently because it has not sufficient tractive power. In Canada the Fontaine is stated to have run a distance of 200 miles at a rate of 60 miles per hour.

will have an aquarium on the ground-floor, and, on the first-floor, nine working cabinets, a hall for conferences, a library, &c. A steam-engine for pumping water has been presented, and set up in a hollowed rock. A total sum of 48,000 francs has hitherto been acquired. The mayor of Banyuls has started a subscription to supply the station with a good vessel. The maintenance of the station, with its personnel, will be at the charge of Government. The laboratory is named after Arago. Another item (which we find in La Lumière Electrique) is that the electric light will be used at this station, the pumping engine being utilised for this purpose.

We come now to dynamics, which is the study combined force and motion, that is, of work; if time in which the work is accomplished is luded in the consideration, of power. We can that work equals force multiplied by the space ssed over during the action of the force, and as unit of space usually assumed is a foot and the it of force a pound, we measure work in footunds. A foot-pound is the amount of work ue in raising a weight of one pound one foot, or exerting a force of one pound through a distance one foot in any direction. Work is considered lependently of the time in which it is accomshed. Power is work considered with respect the time in which it is accomplished: as, for stance, a horse-power which represents 33,000 ot-pounds of work done in one minute or 550 A good deal has been done by the Japanese ot-pounds of work done in one second. The Government since 1868, to facilitate navigation any terms used to express the idea of force and along the coasts of that country. A list of the otion combined can all be seen, by a little thought, lighthouses, lightships, buoys, &c., has lately be synonymous with work. Power is often appeared. There are, at present 45 lighthouses, ed incorrectly for force when the lever and screw classed in six divisions. e being discussed. The weight of a body is the erected in Japan was that of Kannonsaki, at The first lighthouse easure of the intensity of the force of gravity ting upon it. In treatises on mechanics it is the entrance of the Bay of Yedo; it is the work ade equal to the product of its mass by its velo- A private trial trip of the Phosphor Bronze of a Frenchman, was begun in 1868, and lit in ty at the end of one second (32.2ft.) under the steam launch, the property of the Phosphor February, 1869. It rises 187ft., the light is ction of gravity. In order to clearly grasp the Bronze Company, Limited, London, took place white and fixed, and has a range of about 14 eaning of this last sentence we must know what in the Thames, off Westminster, on Tuesday, miles. The last constructed is that of 1813. The mass of a body is usually stated to 22nd inst. This small vessel is built entirely of Koutchinotsou on the Bay of Simabara; it came the quantity of matter in it, and it will at once Phosphor Bronze, and her length is only 30ft., into action last year. It belongs to the sixth perceived that the hypothesis is placed that Of the 45 lighthouses, 11 are of the erences in quantity of matter make proportional her beam being about 6ft., and she attained a order. ferences in the weight, which may or may not speed of 12 miles per hour, which, consider- first order, four of the second, four of the third, true. We have no means of proving that a ing her size, is a remarkable performance. The eight of the fourth, seven of the fifth, olume of iron which weighs 7.2 times as much as chief object of the Company in having so small three of the sixth, and eight below he same volume of water contains 72 times as a craft built, was to test the rigidity of the the sixth. The sixth class contains those

With the view of avoiding the bursting of water-pipes by freezing, a method of making them elliptical in section has been recently patented. As the water expands to form ice, it will alter the shape of the pipe, causing it to become circular in section, and therefore giving more room for the ice. It is proposed to squeeze the pipes into their original shape, when, by a succession of frosts they have been rounded.

light le vinile net more than we being we extimated at 17-8 cubic. m. (say 628 LETTERS TO THE EDITOR

There is thus a gas economy of

the hai in sow brightly illuminated, so that in
i lát, not to speak of the fact that
my orer the enillest print may be read,
whersna, formedy, many parts at the wall and
ourners were in half-darkness. In contrast to
the electric light, the whiteness and steadiness
de the fames are very pleasant to the eye. In a
Winter evening of eight hours' duration, over 140
encic m. of gas would formerly be burnt in the
Piace, whereas, now, with considerably better
ight-effect, the gas consumed in the same time
does not reach 50 cubic m.
At 16 pfennige per
cubic metre of gas, this shows an economy of
14 to 15 marga shillings) on such an evening, so
that the entire cost of construction would be
recovered in one to two years.

[We do not hold ourselves responsible for the opinio ur correspondents. The Editor respectfully request 1ommunications should be drawn up as briefly as posilu ENGLISH MEOHANI0, 81, Tavistock-strset, Coreningerie All communications should be addressed to the Form of w..

J. PASSMORE EDWARDS.

All Cheques and Post-office Orders to be made Payale

peaking of any Letter previously inserted, til tip • In order to facilitate referencs, Correspondasie mentioning the number of the Letter, as semell as the page an

which is appears.

"I would have everyone write what he knows, AR! U much as he knows, but no more; and that not in t have some particular knowledge and expenda only, but in all other subjects: For such perio nature of such a person or such a fountain, at other things, knows no more than what everybody a and yet, to keep a clutter with this line piston d from whence great inconveniences derive their etgan." will undertake to write the whole body of phych: Any person may-Montaigne's Essays.

It is known that the Whitehead vorgelees now adopted by Enziand, Italy, and Germany. In Germany, they are made on a large scale in Berlin, at the Schwartzkopf worka, where they have been considerably improved The improved model has been adopted by Spain, which has lately ordered 100 Schwartz kopff torpedoes, Whitehead system, with 12 launching apparatuses, 12 accumulatore, and 12 compression pumps. The further order of machines and tools required in workshops for making and repairing these torpe Turkey. A patent law has been lately promulgated in does, would appear to indicate that the Spanish French and German laws. It is in substance a copy of the Government have acquired from Messrs. White-take out a patent on depositing the drawings head and Schwartzkopff a joint property in the and specifications. The longest term is 15 years, invention and its improvements. and the annual fee is about £4. patented must come into manufacture in the two The object years following the date of the patent. The penalties for infractions are the same as in other parts of Europe.

It is often found that silkworm-caterpillars come out of the egg at a time when, through bad weather, the foliage of the mulberry has not reached its full development, and large numbers perish in consequence. To meet this evil, a Milan engineer, S. Suzani, throws the eggs into a lethargic state by application of a temperature near zero. They may thus be kept an indefinite time, awaiting the full development of mulberry leaves, and a means is also afforded of equalising the results of years of rich and of poor foliage. The American Society for Silk Cultivation has lately offered 50 dols. premium for the best cocoons obtained in America by coloured women.

A measurement of the proportions of carbonic acid in high regions of the atmosphere has been lately carried out by MM. Muntz and Aubin; the place chosen being the summit of the Pic du Midi, in the Pyrenees, 2,877 metres above the sea-level. (A meteorological observatory, it is known, exists there.) The air that circulates about the summit is generally that of upper currents, and the high velocity of the wind excludes any suspicion of local influence. The air was taken three times daily six days in August, and the average figure arrived at was 2-86 vols. CO2 for 10,000 vols. air. This is very near what was obtained on the plain of Vincennes, and closely similar figures were got in two Pyrenean valleys at 507 and 730 metres' height. Thus it would appear that carbonic acid is pretty uniformly diffused in the atmosphere.

The King of the Belgians' prize of 25,000 franes (say £1,040) for the promotion of science will be awarded in 1885 for the best work on means and measures for generalising the study of geography and furthering instruction in geography in various educational institutions. The competition is international, and the works, printed or in manuscript, must be sent in to the Ministry of the Interior in Brussels before January 1st, 1885.

Some interesting experiments were lately
made at Oldenbrock, in Holland, regarding
the comparative effects of shrapnel fire and
infantry fire at long range. Four field guns
were employed to shoot shrapnel against a low
target 135m. long, representing 100 soldiers
lying on the ground. On the other hand, 100
soldiers lying on the ground opened fire on four
pieces, the artillerymen and horses of which were
represented by wooden dummies. At 1,500 m.
burst and give 36 hits; the infantry fired, during
The artillery fired 30 projectiles, 19 of which
the same time (18 minutes), 7,281 cartridges,
and effected 38 hits
artillery fired 30 projectiles, 24 of which burst
Next, at $1,700 m., the
and gave 75 hits; while the infantry in the same
time (15 minutes) fired 3,870 cartridges, with 43
hits.

In the American Journal of Science for November, Mr. Harkness reviews the different methods of discussing the solar parallax; these being grouped in three classes: I. Trigonometrical methods, II. Gravitational methods, and III. Photo tachymetrical methods. "We only know," he says in concluding, "that the parallax seems to lie between 8.75" and 8-90", and is probably about 8.85". Attack the problem as we will, the results cluster around this central value. All the methods give a probable error of about 0:06, and no one of them seems to possess decided superiority over the others. We have nearly exhausted the powers of our instruments, and further advance can only be made at the cost of excessive labour." It is noted that in the beginning of last century, the uncertainty of the solar parallax was fully two seconds: now it is only about 0.15". The hope of all astronomers that the Venus transit would give the solar parallax within 0.01 were doomed to transit must not in any way be neglected, there is disappointment; and while the approaching less enthusiasm about it.

BRIGHTNESS OF STARS—FOSSIL PAL
NACLES (?)

DISTANCE OF TH MOON FROM THE SUN-ANGULA DIAMETER OF MARS-IRISH FOS SILS-RED STARS. miles as the crow flies from my on tel [19457.]-WRITING these lines, as I do sta must ask Mr. Baird Gemmill Cetter 14 me to defer my reply to his questions millim home, which I hope to do in the course of ce ten days or a fortnight. With Fannin then before me, I shall hope to grestbur answers to some, at least, of his queres

M. A.," p. 264, I may now by the cor former reply to him I have ascertained ther interesting fossil barnacle has been fr This has been named Turriles by De B the last few years, in the Upper Saria ward. The peduncle was fed when detached, are note the geno secting rows of plates, as in La Depa of the Pteropods, and have been of Chitons. This genus Tra of Barrande, has been found in the Size Bohemia, Great Britain, and Siri i No undoubted peduncalated Compet (according to Nicholson) ben je ben from Devonian, Carbonifera len beds. The genus Pole ba been met with in the plant of Lepadidæ are now in th-Comel Tertiary species are few. So place what most people know as Fa pedunculated form which

With reference to the reiterated query

field Slate of the Lower de bela

ships, &c. It would, bower on to
"M.A." says about firing the gr
speaks on the shells of the
referring to the Balamir the
(so far as is at present know
are known in the Paler
exception of the Lias genus omiss
Balanide appear until the
modify this by saying that
the Liss form belongs to the
six valves, and is unsymmetr) a
tergs form the operculum, sed to
This is as much information as I
muscle. One genus of the Verru

Acorn Shells. These make their is ge

my querist without actual inspect

mens.

I do not know for what purpose 45821, p. 255) requires to know the Sun and Moon in Dec. 21st, what degree of accuracy be wisher computed; but roughly cairuls S

wrack bes bende me lind that a day referred to the suruar istiot centres of the Sun and Moon w

The Berlin Society for Advancement of Industry offers prizes as follows:-1. £25 for a thorough inquiry (a) into the quantitative composition and the chemical and photographic properties of the most important kinds of photographic pyroxiling of commerce; (b) into the Mica Masks.-A well-known German manninfluence of temperature of the acid mixture sad in making the pyroxiline, on the chemical facturer of mica wares. Herr Raphael, of Bresian, now makes mica masks for the face, which are and photographle properties of the latter; (quite transparent, very light, and affected nether; into the chemical properties and photographic by heat nor by acids. They afford good protection Influences of the bye-products formed in pro- to all workmen who are able to be injured by : 7798, or thereabouts. duction of pyroxiling, both those arising from heat, dust, or noxious rapears, all workers with I may answer - Ajai” next { the cellulos, and those from natural and arti- fire, metal and glass malers, Root-makos, &c. same page by talks him Boal admixtures of raw fibres (linen, cotton, In all kinds of grinding and polishing wack, the un gostar to the sun acting the paper). 2. The silver medal and £75 for dis- flying fragments rebound from the shed mics of the 27th, st and shour Each Govery of the best material for production of plates of the mask witbort mizing them. These Wi sultant in unga sa 28 Vennela (pinan venneis excepted) for transport of plates are fixed in a metallir frama which is well i the year. A às For Never isolated by means of asbestos be your "Astronomial Notes wtrong nitric acid, attacked by best or stil Theer masks show the p I am ormed with st Miemens regenerative gas-burner was re-turning of the eres in OT ENOVA, End Se against cently adopted for the lighting of Grat weil's mica spectacles, that afford the almanage of pro- speciale inst per S Beer-hall in Berlin. A German paper has the tection to the whole face. In certain cases, the 5-58 for a query 264 p. 150, 20 following data as to this, the first large arrange. neck and shouliers may also be guarded by a sheet tall a 28t to the volumes aast he The hall, lit by four of cloth impregnated with re-grad met 1 NICHT, STL Sie s Biomena' lamps No. 1, is 52 metres long (say by asbestos sheet, attached to the mast. The pecunis osposts sai em 17016), 18m. broad, and 6m. high. The four interval between the mics and the eyes was of may be scarying. Nothing that workmen who have poor resina wearing gar nebushet as comparabit for the en ilustrate the supert semes c No tacles, and of workers wash are or a manag operations wearing ontoured glass spectacles under the mask, without fear of brestare of the ginss, the arts specimens t mica being such a bad conductor of best.

ment of the kind.

burners consume hourly, at the most, 6 cubic Bobrow of gun lnny 212 cubic ft.) Formerly the # was lit with 18 chandeliers having eight large bat-wing burners, and the gas consump