Scientific.

New Zealand Mail, Issue 242, 8 July 1876, Page 6

Scientific.

The Mining Journal says that one of the great objections raised against the Channel tifnnel scheme is the length of time it will take to execute ; but if we are to believe the Liberty, this objection has now disappeared. In fact, according to that paper, the tunnel can be completed in less than six months ! It tells us that a machine has just been invented by which 55 metres of ground maybe pierced through per diem, and it calculates if both the English and the French begin piercing at the same time the tunnel can be cut out in 141 days. The German exploration of the Peloponnessus has begun very favorably, having been rewarded by the discovery of a marble statue of “Victory,” a beautiful Nike, in excellent preservation. The interest and importance of the discovery are enhanced by the fact that the figure bears upon it a perfectly legible inscription, recording that it is the work of Paionios, of Mende, in Thrace, the contemporary of Phidias, and was made by him for the Messenian colonists of Naupaetus, by whom it it was presented as a votive offering to the temple of Jupiter at Olympia, after the third Messenian war, which had continued ten years, and ended in B.C. 455. Considering how few works there are which can with certainty be assigned to the age of Phidias, and how small is the number of those which can be referred to any one sculptor whose name is known to us, the success of the German explorers of Olympia is a lasting gain to the whole world of art. The genuineness of this interesting “find” receives confirmation, as Professor Overbeck has shown, from the writings of Pausanias, in which the votive Nike of the Messenians is described, and an account is given of the facts which had led to its offering, and which differed from those recorded by the inscription. The same writer also refers to Paionios as the sculptor of the statue, and indicates the special parts of the great temple of Jupiter which were the work of his hand.

The Malabar, British troopship, which recently left Portsmouth for Bombay, with the 21st brigade Royal Artillery, is fitted by Messrs. Moses and Mitchell, of London, with a couple ©f automatic ventilators. This new system of ventilation is reported to have answered admirably on board the Osborne royal yacht. An air receiver, 6ft. high and 22in. in diameter, is placed on each side of the ship and connected with pipes Sin. in diameter. These connecting pipes are filled -with water, and the principle of the contrivance is simply this: When the vessel rolls at sea, the water rushes to starboard and forms a vacuum in the port receiver, into which the foul air of the ship is instantly sucked. On the return roll the water rushes to port, drives out the air, and leaves a vacuum in the same manner in the starboard receiver ; and such is the extreme force with which the foul air of the ship is expelled, that it is to be used on board the Malabar for the purpose of sounding a fog horn which shall be heard a mile off.

Nature of a recent date gives a detailed account of a new and most ingenious instrument, invented by Mr. Siemens, for discovering the depth of the sea without the use of the sounding line. This instrument has already been introduced to the notice of the Royal Society. The theory in reliance upon which it has been constructed is that the attraction of the earth varies slightly but perceptibly in various places, according to the depth to which water —which is of less than the mean density of the earth —is substituted for solid ground as a surface material. In the absence of diagrams it would be impossible to describe in detail the instrument itself, but its general principle is simple and intelligible enough. A column of mercury enclosed in a vertical steel tube suspended between two upright, delicate, spiral steel springs in such a way that its weight is balanced by them. The weight of the column of mercury is affected by the variations of gravitation, but the elasticity of the springs is not so affected, and the movements of the spring are therefore a measure of the variations of weight, and these latter are ruled by the varying depths of the water, as explained above. The movements to be measured are so excessixely small that they have to be indicated by means of an eleetridal contact in connection with a micrometer screw, which is of such a pitch, and is connected with a circular plate so graduated as to be accurate -within a fathom. NATURE-PRINTING. The art of nature-printing is attracting some attention just now, in consequence of Sir George Grey having obtained the sanction of the House of Representatives for an address to the Governor, praying him to be pleased to place upon the Estimates a sum of money to defray the cost of a work on native grasses. The proposition which the House has adopted is that a work shall be issued containing nature-printed plates of all native grasses in the colony, and also a letterpress description of each grass. En passant it may be remarked that the value of such a work cannot be ovei-esti-mated, particularly if the subject be treated in the fullest manner possible. Not only should the grasses be described, but their peculiar properties should be enquired into, as also the conditions of soil and climate under which particular varieties best flourish. As was pointed out during the course of the debate, the native grasses are beyond a doubt fully equal to the best imported kinds, and it would be a pity if graziers, from ignorance of the value of the indigenous production, passed it over for the sake of inferior grasses from the old country.

But to return. We have received from Mr. Earle, of the Government Printing Office, of this city, two excellent specimens of natureprinting. consisting of various kinds of leaves, fern and native grass. They are produced by placing the original on a lithographic stone, and from these any number of impressions can

be struck off after the usual method of lithography. He informs us that plates of subjects suitable for the process can be produced at nominal cost ; and from enquiries made, he is of opinion that the production of natureprinted plates by the aid of lithography suitable for practical purposes has probably never before been attended with such success.

The plan to be adopted in nature-printing is to obtain a copy of any material object, such as ferns, leaves, plants, seaweed, tares, &c. —1. Take a leaf and place it on a smooth surface charged with a colored pigment, rub it carefully till sufficiently covered with the coloring matter (or the color may be applied by dabbing it on with a piece of cotton wool), then take the leaf, press it carefully on a piece of clean paper or fabric, the result will give a perfect facsimile of original. 2. Take a fern, place it flat on a piece of satin or other fabric, then with a tooth-brush charged Avith color, sprinkle the Avhole surface by drawing the tip of the finger through the hair of the brush, the result will be a white leaf on a stippled background. Very pretty mats, suitable for the toilet table, &c., can be produced by this method. 3. Very nice results can be obtained with leaves, if not too opaque, by placing them on a piece of photographic silver paper, and exposing to the action of light after the usual method of photographic printing. The foregoing methods are only adapted for the amateur, or when a few copies is all that is required ; but for illustrating scientific works it is necessary to have recourse to other methods. The honor of the first invention ©f nature-printing, suitable for commercial purposes, is due to Herr Alois von Auer, director of the Imperial Printing Institute at Vienna. The process consists in taking any suitable object, comparatively flat, such as a leaf or fern, and impressing it into a sheet of lead or guttapercha, which forms a matrix for producing printing plates by electrifying. Mr. Earle will probably do all the printing for the new Avork, and Mr. John Buchanan Avill likely supply the letterpress descriptive part. At anyrate these gentlemen Avere referred to by Sir George as well capable to do the Avork satisfactorily.