Science Siftings

New Zealand Tablet, 22 July 1909, Page 1155

Science Siftings

BY 'VOLT

No Sand in Sandpaper. x ' TheTe is no sand in sandpaper,' said the manufacturer. 'It is powdered glass that does the business. That's where the broken bottles go to.' He nodded towards a mass of broken bottles in the yard. 'We powder the glasa into half a dozen grades,' he said. 'We coat our paper with an even layer of hot glue. Then without loss of time we spread on the glass pojvder. Finally we run a wooden roller lightly over the sheets to give them a good surface. When in the past they made sandpaper of sand it wouldn't do a quarter of the" work that glass paper does. 5 An Immense Telescope. A citizen of Los Angeles, Cal., has recently given 45,000 dollars for the construction of a 100-inch reflecting telescope, to be used by the Carnegie solar observatory on Mount Wilson. The glass disc from which the mirror will be formed has already been ordered of St. Gobain, 'n France, but it is expected that about four years will be spent in making the disc and afterward grinding and figuring it. Professor George E. Hale, the director of the solar observatory, thinks that no insuperable difficulty is likely to be encountered in the making and mounting of this enormous instrument, which, in light-gathering power, will immensely exceed all other telescopes now in existence. The mirror for the 60-inch reflecting telescope now being constructed for the same observatory is nearly completed. How Sculptors Work in Marble. The artist makes a model first, not always life-size, but almost none of them actually do the cutting in the marble.' This work is' entrusted to highly-skilled artisans, who do the work under direction, the sculptors superintending all the finishing touches, and, on occasion, some of the cutting on the face and hands. The actual cutting of the stone is a most difficult process, and requires great expert skill. In case a full-sized model is made the sculptor sends it to -a professional marble cutter, who roughly shapes the block. The general shape is often given to the block before it leaves the marble yard, in order that certain costs of freight may be saved. The rough carving is then done by the marble cutter, who so shapes th 9 block as to give it the general outline. He first drills a series of holes in the block, and then chops off the pieces. Ingenious Printing Machine. The German Government has recently adopted a novel device for printing and issuing railway tickets. It comprises a machine about 3ft in length by 4ft high and 20in wide, so that it can be placed conveniently beside the ticketoffice window. The machine, which is in operation at Cologne, is designed for use in 1300 stations; but the apparatus can be adapted to any number as reqiiired by the exigencies of the railway by which it is used. The machine is very simple in design. It carries as many printing-plates as varieties of tickets required for issue from the station. The names of all stations are arranged in alphabetical order on a scale. On a ticket being demanded, the clerx inserts a blank piece of cardboard of the conventional size into a sliding carriage, which is the printing apparatus, moves it along until it is opposite the name of the station required on the indicator, depresses the handle, and immediately the ticket drops out imprinted with the name of the departure and arrival stations, date, consecutive number, fare, route, class of carriage, and any other fact that may be required At the same time a duplicate is printe-1 on a continuous sheet, so that no booking operation by the clerk is necessary. No card can possibly be printed by any unauthorised person without being registered on the control sheet, which cannot be altered by the clerk. Misuse is out of the question, and the booking office is proof against theft, since no ticket is of any use until passei through the machine, being merely a blank prior to this last-named operation. Any type of ticket can be issued without delay, including excursion, tourist, privilege, workmen's, season, dog, vehicle, etc. The machine appreciably facilitates the task of the clerk, and tickets can be issued far more quickly than by the existing method, one official at Cologne station having issued 500 tickets in an hour by this machine.