The daily morning journal and courier., 1905-10-06
FINEST OF MEASUREMENTS.
Wonderful Work Done by the Cover
 . Fa,,-co,, oF C~auIay.1z

Wonderful Work Done by the Govern ment Bureau of Standards.
 It seems rather a remarkable thing l that, whereas the governments of Eng
 land, France and Germany have for
 years provided extensive laboratories 1 for the purpose of maintaining cor l rect standard of weights, meausre-
 ments, force, purity, &c., it is only re- | gently that similar office has bsen es-
 tablished in Washington. This ''Bu- reau of Standards" as it is called, is now very perfect and complete, howev- ! CT, says Tit Bits, and may be made use
 of by all who desire information on any scientific point coming under the head of weights and measures.
 If you desire, for instance, to know in what degree the heat of your body
 expands the works of your watch, all you have to do Is to write to Washing ton and the officials there will have
 great pleasure in relieving your anxie-
 ty. on the point. though you will have to
 pay for the time occupied in working out the knotty problem.
 In a lecture delivered some time ago
 Professor William Hallock of Columbia
 university, who is connected with the
 Bureau of Standards, gave some inter-
 esting particulars relative to the ad-
 vantages and value of the new institu-
 ton. Should you be a purchaser of
 scientific instruments, incandescent
 lamps, hydraulic machinery, Sc, and
 wish to know whether they conform to
 the standard recognized in other parts of the world, you may send them to Washington and receive all the infor- nation you desire.
 "In 1873," said Professor Hallock, in
 his recent address, there was estab- lished in Paris, through the co-opera- ton of several countries, including the United States, what was known as the International Metric commission, whose business it was to manufacture copies of the standard meter and the stand l ard kilogram. But the meter and the | kilogram were defined ong before that | by the French Academy, the standard | meter being one ten-millionth of fine | distance of the earth's surface from the | pole to the equator, and now represent | ed by the distance between two lines on a metallic rod preserved in the archives | of the International Metric commission. l Two of these meter bars and two of | the kilometer bars were turned over to | the United States for permanent reten- tion, and are now in safe keeping in Washington. To illustrate the delicacy or the processes employed by the com mission will give one instance. When comparing two kilogram blocks their weight was noticeably affected by their position on the balance scale. Side by side they weighed exactly the same, whereas when one was placed on top of the other the under block was the heavier, for the reason that gravi- tat1on decreases as objects recede from the center of the earth. That process represented a delicacy in weighing of one part in hundred million, and in order to show the difference represent ed by moving the blocks as indicated it would be necessary to weigh to about one ten-thousandth of. a grain.
 Tn our bureau of standards it is now possible to measure temperature to a nillionth of a degree. One of the re- cent determinations in measuring rays 'f heat takes as the unit the amount of heat thrown off by a candle six miles hstant The instrument used to record these radiations is an exceedingly sim- ole affair, consisting of very light mica disk delicately suspended in bulb from which most of the air has been exhausted. When the radiations l From the candle fall on this disk they heat it sufficiently to force it back. l
 As rule, light lends itself very nicely to extremely fife measurements. It is mo trick at all to calculate accu- 'ately the thousandth part of the width of human hair, or even something hat is amost invisible to the naked eye, such as a spider thread, this being possible through the interference of waves of light. If he have two systems ., ot waves which come together so that 1. he crests of one system coincide with he crests of the other the two systems are then in step, as we say, and help each other On the other hand, if for =. my reason one of them is a trlf1e be- ,, 1lnd they come in out of step and neu- !