Science & Invention.

Alexandra Herald and Central Otago Gazette, Issue 696, 6 October 1909, Page 7

Science & Invention.

THE FIRST TO ELECTRIFY RAILWAYS. Sweden will be probably the first country in the world to abolish steam "locomotives on all its rail-roads. For Sweden has no coal of its own. and has to import all that it uses. Sweden began in iqo6 to experiment with electric traction on its railroads. Electric motors were tried first on a small stretch of road and the results were so satisfactory that it has been decided to electrify all the lines. The Government has bought several large waterfalls, which will furnish the power; five central hydro-electric stations are to be established for the operation of a first section of abovt 2000-kilometres, and secondary stations, situated about 20 miles apart, will send the motive power in two directions in order that any point on the svstem may receive power from two different stations. These generating stations will also supply motive power direct to factories, the motors of

which are now run by engines burning petroleum in their furnaces. The electric motors are to run at sixty-kilometres an hour for. express trains and forty-five kilometres for way trains, which is a ljttle more rapid than the speed at which the trains run to-day. The Swedish engineers calculate that electrification of these 2000 kilometres of railway will bv 1020 effect a saving of about £72,000 a year in the operation of the roads. A "FOCPHONE"! INSTRUMENT TO PREVENT COLLISIONS. . The fogphone of Mr. R. H. Marriott is designed to prevent collisions at sea by a combination of wireless telephony and the ordinary fog bell or the submarine bell. Its action depends upon the fact that the sound of the bell travels in air about icoo feet per second, or slightly faster in water, while the transmission of the same sound by the wireless telephone is practically instantaneous, or at the rate of light —about 186.000 miles a second. 'As the man in the pilot-house catches the sound of the bell in the telephone receiver, he presses a button which starts an instrument resembling a stop-watch. When the. sound of the bell arrives by air or water waves he stops the instrument, and the dial —instead of indicating seconds like the watch—shows the miles and feet the sound has travelled. At the distance of two miles the air sound would be heard abou't ten seconds after that of the telephone. When the bell is next heard, the indicator shows whether the distance has increased or diminished, and thus the navigator is notified if there is danger of collision.

THE PULSE AS HEALTH INDICATOR. Ignorance regarding the pulse is common enough. Here are a few facts concerning the interesting little indicator in question which it is well all should become acquainted with. A regular and steady pulse- which is not easily put out of measure 'by pressure always indicates a healthv condition of the system. If. however, there is an intermittent beating of the pulse, it is an indication that .the heart's action is faulty: You need not. however, take alarm, since there is no portion of the body, no matter how vital, which does not get out of order many times in the year.

If you are a healthy person in the prime of life, your pulse will move at the rate of 72 beats to the minute, though the number will vary according to the hour of the day. Do not think, however, that you are more vigorous than others because your pulse beats at the rate of 80 or go to the minute. One whose pulse beats at the rate of only 40 or 45 is as likely to be quite as vigorous.

The French doctor Quetelet has drawn up a table showing the action of the pulse at different stages of life. At birth the little indicator gallops along at the rate of 136 to the minute: at five years, at the rate of 88; from ten to fifteen, at a rate of 78. Here a drop occurs, and between fifteen and twenty there is a fall to 69. Between twenty-five and thirty the rate is 71; between thirty and fifty, about 70. During the past few years the exact state of any given heart has been gaugable, owing to the invention known as the sphygmograph, which registers the action of the pulse and so tells the truth about the heart. Any doctor can tell you whether your heart is weak or strong, and, without a doubt, whether a sudden death is likely to be your portion.