SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XLI, Issue 12663, 17 September 1904, Page 6 (Supplement)

SCIENCE, MECHANICAL INVENTIONS, ETC.

INDIAEURBERIN ITS INITIAL STAGE. -As a result of the demand for pneu- • tnatic-tired vehicles rubber is now one of, tin-* chief exports of seine South American countries. Sir Martin Conway, in his book, "Climbing , and Exploration in the Bolivian Andes," gives mi account of the way in ■which the gum is procured and. prepared. The -workman, starting early in the mom-' ing—for ■•when the sun is high the trees cease to bleed—carries with him e number nf little tin cups. He makes one 05 more incisions in! the bark of the tree and attaches one of the cups below each cut by pressing it into the soft bark. A strip of bark all down the tree one-third of the circumference in width must , however, be left unbroken, or the tree would bleed to death. The cups collect the drops of sap that exude from the wound in the bark, and the worker proceeds from tree to tree until ho has tapped from seventy to a hundred trees. When he has brought the day's gathering to his' hut he lights a fire of palm wood. He places a funnel over it to collect the smoke, and then, taking a kind of small wooden paddle, dips the blade into the liquid, which cavers it with a thin coating, lie now holds the" paddle, over the fire-in the smoke, : turning its faces alternately to the heat. The coating of milk-like ■ sap is thus rapidly smoked and coagulated into solid cured rubber. The paddle is then dipped again, and the process repeated until a large bulb or' ball has been formed. When this' has reached a con veil size it is slit,down the sides and stripped from the paddle. The lumps thas formed are ready for export, and are the pure rubber of commerce.

UTILISING THE EXHAUST FROM LOW PRESSURE STEAM TURBINES. . According to the Elektroteckniseheßundschau, a new process lor utilising exhaust steam to produce power in low pressure steam turbines has. been developed in Germany.: The device is especially intended for utilising: the -exhaust from intermittently working mining engines. While an ordinary condensation in most -of-these engines will :have a very slight effect {the vacuum in the cylinders being negligible, and considerable condensation looses being caused by a high cooling of the steam sylinder during stoppages), the new outfit will permit the use of the exhaust from these machines so as to secure higher economy than can be obtained, for instance, in the case of a highclass triple-expansion engine. From the exhaust steam from a hauling engine 500, and from tinst from a reversing machine 1000, electric: hoiae-powei may be generated. Moreover, the first- cost is much lower: than. in a .high-tension steam plant 'of. the same output, while there are no expenses for operation worth' mentioning. The principle ©! the process consists in storing the exhaust steam issuing in variable amounts from the intermittentlv working engines in an. exhaust steam accumulator and of transmitting the stored.-steam in a! uniform manner, to a low-tension turbine. The latter, after' l: re- .- ceiving the steam, as a rule at atmospheric tension, will give-it off again at the condenser tension. In the accumulator the exhaust steam has a pressure by 0.15 to 0,0 atmospheres higher, the pressure varying within these low limits with tue charging and discharging of the apparatus.

THE BEXER MACHINE-GUN AT MSLEY. The Kfcxer machine-gun was fired for the'first' lima in public, ii Pierce of, the Prince and Princess of -Wales;- at t« is " ley, on a recent Saturday. The. gun lias hoen adopted by the Danish Government in both its naval and military services, but more particularly for the cavalry. /it is a single-barrelled rifle v 14$lb in weight, and the barrel is encased in a slotted-, jacket for cooling purposes. It is mtended to be fired from a two-pronged rest, attached to the fore part, and which '3 folded on the barrel when not in use. Five hundred or six hundred rounds can " ■bo fired consecutively with impunity, that is without undue heating of the _ barrel, which is, moreover, grooved on the outside to assist in the cooling process. But 1 the "Utt can be fired at the rate of fifteen shot? a second, and from 200 to 300 aimed % shots can be delivered, the marksman covering his object before pressing the j trigger, lit othar machine guns firing is j dependent on automatic action, and can- i noD be controlled until the feed-case is empty or .removed.. The exhibition of the gun was merely a passing, deraonstra-' tion of its rapidity of fire, the operation being carried out under the superintendence of Mr. G. Accles. The Prince; of ■ Wales and Lord Roberts were much struck with the gun's simplicity of construction when it was taken to pieces by Mr. Sufill,- ■ the proprietor, previous to the discharge' of over 200 rounds at the target with rattling speed and telling effect.

. : ' TH.E : SUPPLY OF IVORY. % \ -] During a recent visit to the London Docks j Her. Majesty the Queen was informed that the stock of. ivory then shewn represented on an average the annual slaughter of some 20,000 African elephants. This statement has been contradicted in two 'letters' in. the daily papers. In one of these Messrs. Hale, ' of 10, Fenchurch Avenue, state that at, least 85 per cent, of the supply is "dead ivory," mainly obtained from hoarded stores of the African native chiefs, who are shrewd enough tc nut their commodities on the market only in driblets. The most interesting: wart of the letter is, however, the statement that' the great bulk of this hoarded ivory is obtained from " elephant cemeteries —spots met with here and there in Hie jungle where elephants thave resorted fof centuries to die Much of the ivory that.cowes to the. market mav, therefore, according to this letter 'be several hundred years . old: 1 m marvel is why it is not devoured irf the jungle by porcupines, as certainly happens with tusks of the Indian elephant which are left in the jungle. ..The letter adds that very little ; ivory is now obtained by hunters. : -..i-.. MOTOR WATER CARTS. ■'The long-expected motor water carts begin- ' ning to make their appearance in Paris streets are' highly successful. This new, useful municipal automobile carries 1100 ' gallons. The maximum speed is 184 m"=' an hour. Each can be filled in six .niuuteis.-and can; sprinkle a -mile of roadway 45ft wide m 6V minutes. Steam is the motive power, a SB-horse ■ power engine being used in connection with a bevel 'drive and: live fear axle. A connection between the-wheels and the water jets regulates automatically the output' of the latte;,' according to the pace of the cart, and closes them altogether when the vehicle stops. • *_•'■-. ; A NEW TYPE OF BOILER TUBE. . . A corrugate boiler tube has been, invented. The makers of this tube claim greater heating surface and a longer life than that of the ordinary straight tube ; alsc freedom from live sparks end leaky ends. The hot gases are retained longei with this tube than , with the straight lube on account of the rotating motion induced by the spiral , form of tho tube. The tube is naturally elastic, due to its spiral form,, which relieves the strain on the hue sheets; and prevents leakage at the flue ends. Tests made. show that it. will stretch |in in 16ft befoie the elastic limit, is exceeded. These tubes have been tried for five years on a number of American railway? and they have given satisfaction, ■ '■■-..;•■ OSMON, A NEW COMBUSTIBLE , FROM PEAT. A new form of combustible, known as "osraon," has been lately produced in Europe from raw peat. Of the 90 per cent, water which the peat contains, from 20 t0:25 per cent, is eliminated by an electric process. A direct current is passed through the mass of the peat, contained in a suitable tank. tinder the action of the current, the water collects at the negative pois and flows out by openings in the side of the vessel. In carrying out the process the inventors use from 10 to 12 kilowatt-hours per cubic yard of raw material The process lasts about an hour and a-half The electrically treated peat is then dried in the ordinary way and reduced tv mail, pieces. a .crusher. ,It is delivered to the > trade in the. form of balls, or briquettes.- The heating power of the new product is considerable. No trace of sulphur is found, and i 1 does not thicks or leave much cinder.