SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XLII, Issue 12853, 29 April 1905, Page 4 (Supplement)

SCIENCE, MECHANICAL INVENTIONS, ETC.

FINDING BY ELECTRIC WAVES. A description* of an apparatus and method used in locating lodes by means of electric avert appears in tho Electrochemist and Metallurgist:—"The transmitting apparatus consists of an induction-coil adapted to deliver, when required, a very heavy secondary discharge into a glass condenser from which wires connect to portable electrodes. The receiving-circuit consists of two telephone receivers, each of 500 to 900 ohms resistance, connected to the exploring electrodes through a. series-parallel switch. On earthing the transmitting electrodes. Usually about 100 yards apart, « field of force i<s created in the earth's crust, somewhat similar to an exaggerated field of force from a large horseshoe magnet. With a suitable amount of condenser in action and proper adjustment of. spark-gaps, the telephones connected to the receiving electrodes give a note audible at least a mile away. A good conduct ing-lodo changes lie shape and intensity of the normal field, elongating it in the direction of the strike. Waves passing into the lode at great depths are brought up to tho surface. Heuce there is a cou- j centratiou of energy over the apex of the j lode and a corresponding increase ot the' bounds in tho telephones when in the neighbourhood of the lode. With lodes which act as insulating bodies the field is never elongated, but possesses its normal shape. On. encountering the lode the waves are brought to the surface 'of the ground, since they cannot pass through the lode, and are. concentrated in the space between the apex of the lode and the earth's crust; and when the telephone electrodes arrive at a point over a odd of thL kind the increase in sound is sudden and intense. Further particular - as to the behaviour of vertical deposits and faulted lodes are given by the author.*'

AUTO-PASTEL. Auto-pastel is the name of a new photographies paper which has been introduced by the Autotype Company, whose name is so much identified with the development of carbon-printing. The charge of want of permanency which was at oue time with such good reason brought against photography is no longer true, for the modern photographer has many prepared papers to choose from, prints upon which cau be guaranteed not to fade. The new paper is one of these, for it- is coated with a permanent pigment, which' is made sensitive to light By immersion in a 5 per cent, solution of bichromate of potash. After drying, the paper is exposed to light beneath a negative in an ordinary printing-frame, and is then developed, the developing fluid being simplv water. A bath of cold water is followed by floating the exposed paper on .•water at a temperature of from one hundred and twenty to one hundred and fifty degrees Fahrenheit for two or three minutes. Then the paper is turned upwards and gently brushed in all directions with a large camel's hair brush, certain parts being rendered lighter according to the taste of the operator. A final wash in cold water completes thin very simple method of making a photographic print. THE PIANOFORTE. The evolution of the most- popular of our musical instruments, the pianoforte, formed the subject of a lecture recently given by Mr. George Rose in aid of the funds of the Music Trades' Benevolent Society. It •will no doubt- come as a surprise to many {to hear that Nebuchadnezzar's dulcimer and psaltery were the precursors of the modern domestic instrument, and that the psaltery, •which survives as the zither .is the ancestor" of the spinet. About five hundred years ago a key-board was added to the psaltery, and it became the clavichord, an instrument which was long in vogue, and which ladies would play standing in front of it. This was the favourite instrument of Bach, so that we may be sure that it possessed several good points. He did not care for the spine;-, which he found wanting in soul; and as for the then newly invented pianoforte, it was far too clumsy and harsh to win his tasie.- The harpsichord was the direct" predecessor of the pianoforte, and was far morn ambitious in its design than any of its predecessors, for it had three strings to each note, and was generally furnished with two rows of keys. The Venetian swell common to organs was inTented by Schudi, the founder of the firm of Broadwood and Sons, who was making harpsichords in London in 1723. This method of controlling the volume of sound was applied by him both to harpsichords and pianofortes. It is interesting to note that the earliest recorded public performance on the pianoforte took place at Covent Garden Theatre. London, on May 16, 1767, •when the playbill announced that at the end of Act I. of the " Beggars 1 Opera" Miss Brickler would "sing a favourite sons from 'Judith,' accompanied by Mr. Dibdin on a new instrument called the pianoforte."

WINTER EGGS'. A if.iethod by which hens can be induced to furnish eggs in autumn and winter is called the " dual system," and consists in keeping the hens in couples in coops of a certain area with a small run attached to each. Much attention is paid to the nature of the soil and to food and cleanliness. Fowls have been kept- under these conditions for several years, and the yield of eggs has averaged for the past five years one hundred and fourteen for each fowl. The system advocated involves neither radical changes nor expense, and is worthy of a trial by all who keep fowls. 'EXTINGUISHING FIRE ON SHIPBOARD. Fire is under all circumstances a most dreaded agent of destruction; but it assumes a peculiarly terrible aspect when it breaks out in the hold of a, vessel which is hundreds of miles from land. Many suggestions have therefore been made with a view to quickly quench such a conflagration or to make its occurrence impossible. One of the latest is described by the Railway Supplies Journal as the invention of Dr. Staff, of St. Ives, Cornwall, who proposes to fix in the holds of a ship tanks containing pieces of broken marble or chalk. These tanks would be connected with the main dock by meant of pipes, and when a suitable acid. solution was conveyed to the tanks through these pipes sufficient carbon dioxide gas wouh' be generated to cover the cargo and prevent or stop combustion. Another important result would be attained in the extermination -.-f anj rats which might infest the ship. Thr inventor is apparently not aware that carhop dioxide is now obtainable commercially in liquid form, and that the samo Jesuits would be brought about by releasing the compound from its s>teel containing-cylinder into the hold of the ship. The necessity for special apparatus would thus be entirely avoided, as would bo the handling of corrosive acid. '

HARNESSING NIAGARA. Niagara River develops eight and a-half million continuous horse-power. This rate of work is entirely beyond human conception, but some faint idea of it may be got by reference to the amount of coal that would be consumed to develop energy at the same rate. If two pounds of coal were burned per horse-power per hour, the weight consumed in that time, to equal the work ■of Niagara River, would be 8500 tons. Con- j tinuous work for one year at this rale would require 74,460,000 tons of coal, or more anthracite than the United States produced in the year 1900, when the entire output was 57,464,235 tons. Thin prodigious power, except the relatively small amount that is devoted to useful work, is now joutinuous'.y expended in carving a deep, narrow channel through , the strata of rock, about '10 miles wide and more thaiu 500 ft thick, that separate Lakes Erie and .Ontario. Already the strong hand of the water, armed with stones and silt, has carved the -Jr great canyon of the lower river, about t-ix " miles long, from Niagara Falls to the loot "fl of the escarpment at Lewiston and Queeustnn. Tn many thousands of years to come, % tf the work of the river is not interrupted, firL'''*the 14 miles of canyon that remain to be <l excavated between Niagara Falls and the foot of Lake Erie will be completed. Then f - (that lake will »arrow down to » liver and ,v ( the falls will be transferred to Detroit J