POPULAR SCIENCE.

Gisborne Times, Volume XXX, Issue 3556, 22 June 1912, Page 3

POPULAR SCIENCE.

WANDERING PLANETS.

The irregularities of the groat group of minor planets forming a ring between Mars and Jupiter are sensational. Several hundred of them are now known to follow tlieir normal omits between the two great planets; but in 1898 one of them—now called Eros—was found to cross the.orbit of Mars, coming nearer to tlie earth’s orbit than any other body except the moon. In 1900 one of the planets was discovered going beyond the orbit of Jupiter. And now .four with this peculiarity are known, and have teen named Achilles, Hector, Patroclus, and Nestor.

TEST-FOR FIRE DAMP. One of the simplest of the many, suggested' tests for fire-damp in mines is that .described the other day iby Henry Briggs to the Scottish. Society of Arts. It is an attachment that may be applied to any oil or spirit safety lamp, and consists of a loop, of copper wire supported on a brass rod ■passing through the oil vessel. To make a test the loop is moved into the flame. This becomes instantly noil-luminous, blit if fire-damp is present in the air the gas-cap is clearly seen. 'Hie test can be made in a moment at any time, without turning down or putting out the light. It is claimed that the percentage of firc-

damp this method' will detect is exceedingly email, and the results of triais in both laboratory and mine go tot show that this is one of the most sensitive, accurate, and expeditious means of revealing tlie presence of inflammable gas in mine or other air.

TRANSMISSION LINES. -

It seems that the breakage of electric power transmission lines is often due to a peculiar swinging motion which such lines spontaneously assume when traversed by tlie current. What causes this swinging js not definitely known, but it is believed to be an electromagnetic phenomenon due to the magnetism of the earth. In experiments made in France it was found that a, wire COft.’ long began swinging with an amplitude of 24in. when carrying a- current of 20,000 volts. According to a French authority, the geographical direction of the transmission lines has much, to do with the seriousness, land frequency of disturbances duo to atmospheric causes, the lines running north and south being most frequently subjected to trouble. Also, that in hilly country, lines suspended so- as to form a. vertical zigzag line are 'much affected-

ELECTRIC ALARM FOR CLOCK. The method of putting an electric contact upon tne dial of *<a '.'arm clock in order to'ring a hell when the hands come to the right point is well known, as is also the- method of wrapping a cord about the winding key so as to have it pull a switch. However, all these eases imply modifying the clock in one way or another. Wliat is desired is not to make any change whatever upon the clock, and this is realised in a vibration method used by a. French inventor. All that is needed is to put the clock on a shelf or the cover of a box, the shelf having a main flat part for the clock and in front a sloping part or slideway. On the slideway a metal bar is laid, and below it are two contacts such as screws or nails, so that when the alarm goes off the vibration of tlie shelf will cause the bar to slide down and make the contact. Au alternative scheme is to pivot the bar at one end, with a contact stud lying below the other end. In this case one wire is connected to the bar and the other to the stud, so that the liar swings down and makes the contact. The battery and electric hell can be placed inside the box, and tlie top is used for the. shelf.

PHOTOGRAPHING M-ICROBES. Successive photographs of living objects in rapid motion, magnified 600 to 1000 times, have been taken by M. Comandon, a French scientist, at the rate of sevei-al thousand per minute, and the many kinematograpli films prepared have been used by the firm of Patlie Freres for some, marvellous exhibitions on tlie screen. In making the pitcures, the ultra-microscope was used, the objects being illuminated by powerful rays of light from one side. Among the most interesting films are those of the blood as it circulates, with its normal and abnormal contents, the tail of a tadpole, showing a number of little bloodvessels—each 1-2,500 th inch in diameter—through which the red corpuscles pass with the circulation, while the colorless cells or leucocytes change about with an independent motion of their own. In some films these leucocytes, now known to lie the blood’s scavengers, are eeen in. the act of seizing and absorbing foreign matter, such as diseased cells or microbes. Such pictures as these are reproduced on the screen much less rapidlyi than they are taken, thus bringing to the eye’s perception the quick darting about of the organisms that swarm in the Wood in certain diseases*; hut another class —like those of growing plants—are taken very slowly, and exhibited at a rate quickened to make the motion visible.