POPULAR SCIENCE.

Lake Wakatip Mail, Issue 2138, 1 January 1897, Page 3

POPULAR SCIENCE.

Photography and Crime. I From" the "Tagliche Rundschau" we learn of a practical use of photography in the detection of crime that is novel and ingenious. The murder of a woman was traced to one of two men—her husband and a neighbor. Each had hairs upon his dothes. Dr J-eserich, "the inventor of criminal photography," photographed the clothes cf the suspected men, and the cameras disclosed the fact that the hairs on the husband's clothes were from his wife's head, while the other prisoner had hairs from his awn head en his clothing. The same scientist bos shown that the differences in inks used in writing and in altering a document can be shown clearly in a photograph of tJie document. Even on surfaces from which, to the eye, all trace of writing: has been erased, the camera reveals legible characters ; and the forger or tfcief fails of his purpose of Irrevocably destroying the original purport of the document with which he tam pers. Were all possible agencies known to science used by scientists m the detection of envne, these would r K>e "troub lrt, is times" ror malefactors.

Coloring Leather. A new process of coloring leather, in which electricity is utilised as the active agent, is being exploited in Germany. The leather Is placed upon a zinc table, which forms the positive pole. The dyeing material is poured over this, and the negative pole connected to the leather. Under the action of the current the coloring matter penetrates the leather, and patterns may be designed upon the surface by covering it with a pattern

plate connected to the negative pole.

Visibility of Lights at Sea. A commission appointed by the German Government to-study the visibility of lights at sea has concluded that a white light of one candle power is visible at a distance of 2800 yards on a clear night, and at a distance of one mile only on a rainy night. It was further found that when a white light of one candle power was visible at a distance of one mile, one of three candle power was visible at two miles, of ten candle power at four miles, and of nineteen candle power at five miles. A green light of one candle power is visible at .8 of a mile, and the lighting powers of such lights to be seen at distances of one, two, three, and four miles, must be two, fifteen, fifty-one, and 106 candle power respectively. The best glass is a dear blue green, while for the red light a copper red is the best. Ships with Gas Engines

Ships with gas-engines are apparently gaming favor in France. A new boat of this type has recently been put in service for the Havre-Rouen-Paris line, the speed obtained being seven knots. It is 100 feet long, with 7ft draught, divided into four water-tight compartments. The gas is supplied frcm on Shore, and is stored on board in a steel holder, an accumulator, composed of steel pipes, under a pressure of 95 atmospheres, about 8501bs. The engine employed is a two-cylinder one, of 40 borse-power.

An Ancient Wall. The preservation of the remains of the famous wall of Antoninus, between the Firths of Clyde and Forth, built in 140 A.D., has been occupying the attention of the National Trust for Places of Historic Interest or Natural Beauty. Communications have passed on the subject between the Trust and Lord Balfour, of Burleigh, Secretary of State for Scotland, who has displayed considerable interest in the matter, and has visited the neighborhood of Falkirk, in order to examine personally what remains of the wall. There is reason to believe that the landlord along the line of the wall will co-operate in the work of preservation.

The X Rays Again. Tbe horror of being buried alive is with many people so great that they leave instructions for some small multilation to be inflicted upon them when the breath has apparently left them.so that assurance may be made whether they are really dead or not. But, thanks to the X rays, a Chicago physician has changed all this. He announces (says the "Photographic News") that those rays will determine positively whether real death has occurred, or whether the patient is in a trance. Dead flesh, he says, offers more resistance to the penetration of the rays than living, and a glance at the radiograph of tlie person would determine whether it was tnat of a corpse or not.