Scientific and Useful.

Patea Mail, 2 June 1882, Page 2 (Supplement)

Scientific and Useful.

CRYSTALLISATION. Mr. Braham, F.C.S., in a recent address on “ Crystals,” said he considered crystallisation to be one of the grandest studies that the chemist and physicist can pursue, and one in which the microscope played a most important part, for by its use the time at which crystals were to be discovered was shortened. He considered crystallisation to be the first effort of matter in building up a structure, and to observe the manner in which crystals form under the microscope, we have ocular demonstration of the energy exerted by matter under certain chemical and physical conditions. Speaking of the time which was required to produce such crystals as diamonds of large size, he gave it as his opinion that it was impossible to conceive the time they had taken to form, and their .purity depended on circumstances of large masses of matter in a solution crystalling heterogeneously until nothing but the pure element was left, and that a slow process of formation through ages completed it. At the close of the address the sealed tubes were exhibited under glasses.

AUTODYNAMIO WATCH. The watch recently referred to, manufactured by Mr. Frederick Hitter, Loessl, is in a box closed on all sides, and does not require winding up nor to be moved, no external action being required to keep it going continuously. The watch is kept in motion by the variations in tension of the atmosphere which take place continuously on all parts of the globe, so that the power which acts in the interior of the motor ought to last for ever. The motor contains neither mercury nor any other liquid, all the parts of the watch being of solid metal. The watchwork is put in movement by a heavy weight, which remains always the same, and is appended to a roller. The function of the motor is then to provide that this weight, which acts as an accumulator, be kept constantly at the required height. The chain which carries the weight roller is a closed chain, and goes on one side through the watchwork, on the other through a winding-up apparatus, which is regulated by the motor. A compensation pendulum provides for the regularity of the going. When the watch is laid where no trembling, rising, or falling motion' occurs, and is regulated according to the latitude, it requires no looking after, and is not affected by dust, being closed on all sides. MEDICAL TELEPHONY. Professor Bell has submitted to the Paris Academy another electric method (in addition to that of the indication balance) for detecting a projectile in the human body. It consists in inserting a fine needle near where the ball is supposed to be. This needle being connected by wire with one terminal of the telephone, while a metallic plate laid on the skin is connected with the other terminal, when the point of the needle reaches the ball a current arises (the ball and the metallic plate naturally forming a couple), and a sound is heard in the telephone. The needle may be inserted in several places with little pain, and the pain may be prevented by means of ether spray. The method has been tested on a piece of beef containing a ball. Contact of the needle with bone gave no sound, but there was a distinct sound whenever the ball was reached. LIGHT AND COLOUR, It is known that white light may be wholly extinguished in passing through two coloured glasses of pure and different colours— e.g., a red glass and a green glass. To prove this, in a lecture Professor Dubois takes two pieces of wood (like those used for lantern slides) with equal circular openings in the middle. Two rectangular pieces—one of green, the other of red glass—are, by means of screws, fixed between the wooden pieces at right angles, one edge of each crossing the hole diametrically. The circle obtained in projection is divided into four sectors —one white, another red, another green, and another black ; the last being that in which the two pieces of glass are superposed. This experiment is the opposite of that which consists of superposing, by projection on a white screen, a red beam and a green beam giving white (red and green being complementary).

A novelty in canal boats is one built at Wiscasset, Maine, which is propelled by air. The air is forced downwards, and passing backwards escapes in an upward direction at the keel, propelling the boat ahead by its impact with the water. Of course, it is claimed to be a success. It is known that deaf mutes can be taught to speak in a manner. According to Mr. Element, the individuals so taught have the peculiar accent of their native place. Since“thcy cannot have acquired this by imitation, being deaf, he supposes that the fact indicates organic conformations similar to those of their parents: a new example of physical resemblance, transmitted hereditarily.

A compressed air-motor has been lately tried on one of tbe New York elevated railways with satisfactory results. The motor carries four reservoir (auks, in which air is compressed to 580lbs. on the square inch, and after making the double journey the pressure is reduced to 1251b5. With proper facilities it is said the motor can be charged in about three minutes. The Midland Railway Company are considering a scheme for lighting the Erewash Yalley section of their line by means of electricity. The section extends from Chesterfield to Nottingham, and engines and dynamo-machines will be erected at cadi cud. On this part of the Midland system, junctions, sidings, and stations are very numerous, and it therefore offers a favourable site for an experimental trial of the electric light. In Chicago an experiment is being made with a wire-rope tramway, in which the rope is carried in a tube sunk between the rails, the connection with the car being made by means of steel gripping bars which pass through a groove in the tube three-quarters of an inch wide. Interference with ordinary traffic is completely avoided, aud if the experiment stands the test of winter, the tramway companies in other towns have undertaken to employ the system.