Mat 25, 18S3.] 



SCIENCE. 



441 



FRIDAY, MAY 25, 18S3. 



INTERNA TIONAL BUREA U OF WEIGHTS 

 AND MEASURES. 



In compliance with tlie requirements of tlie 

 nineteenth article of the regulations, the inter- 

 national committee of weights and measures lias 

 issued its report for the year 1882, and of the 

 present condition in the progress of its im- 

 portant work. It is the most satisfactory 

 report so far made ; and it shows e\ery thing 

 to be in such good order, and working so 

 well, that the delivery of the international 

 standards may be expected to be begun dur- 

 ing next j-ear. To the present time the prog- 

 ress has necessarilj' been slow, as the impor- 

 tant questions of means and methods had to 

 be carefully considered before adoption. Now, 

 however, we see the methods settled, the 

 means at hand, and the contracts let for the 

 deliverj- of the bars for the international metres, 

 and tlie ingots for the kilograms. 



The report covers the operation of the cal- 

 endar year 1882. During the year important 

 advances were made in the instrumental outfit. 

 The universal comparator, which was ordered 

 in 1877, and was for four j'ears in process of 

 construction by Starke & Kammerer in Vienna, 

 was received at Breteuil in November, and 

 is now undergoing a thorough examination 

 and testing of all its parts, previous to its use 

 in determining the values of the new line 

 metres. 



A contract has been entered iuto, between 

 the bureau and the Societe genevoise pour la 

 construction d' instruments de physique et de 

 mecanique, for the delivery, by the latter,- of a 

 comparator for testing base bars, whether of 

 line or end measure, of lengths up to and in- 

 cluding four metres ; the outfit of tlte compara- 

 tor to include two four-metre line-standards, 

 each subdivided into single metres bj- lines 

 drawn on platinum-iridium plugs inserted at 

 proper intervals. These standards are to be 

 of wrought iron, T-shaped in cross-section . In 

 addition to the subdivision into metres, one of 

 these standards is to have two additional lines 

 0.051 metre within the four-metre lines (the 



No. 16.— 1883. 



space so marked serving as a double-toise 

 standjird), and two lines 0.060 metre without 

 the four-metre lines (this space serving as the 

 standard for comparison of four-metre end- 

 measures by the use of contact cj'linders) . The 

 contract price for this apparatus, delivered and 

 mounted, is 34,000 francs. It is to be deliv- 

 ered at Breteuil before the end of Jul3- of this 

 year. 



The balance for vacuum weighings was re- 

 ceived, but certain defects in its construction 

 required it to be returned to tlie maker for al- 

 teration. Unhappily the condition of his health 

 has delayed the necessaiy work ; and, as it did 

 not seem probable that he would be able soon 

 to give the matter his personal attention, the 

 execution of the details of alteration has been 

 intrusted to other hands, and it is expected 

 that the balance will be in satisfactory working- 

 order before the end of the present year. Un- 

 der the care of M. Marek, the other balances 

 have been placed in position ; and every thing 

 is in readiness for the weighings in air and for 

 the hj-drostatic weighings. 



The Fizeau expansion apparatus has been so 

 modified as to admit of experiments in vacuum, 

 and the tests of the modified apparatus have 

 been most satisfactorj-. From the observations 

 for the expansion of the platinum-iridium tripod 

 of the apparatus, data were obtained for ascer- 

 taining, more surely than ever heretofore, the 

 index of refraction of air between 0° and 80° C. 



The air-thermometer apparatus has been 

 perfected ; and it is hoped that the comparisons 

 of thermometers, retarded by the illness of Dr. 

 Fernet, will soon begin. 



The contract for furnishing the bars for the 

 metres, and the ingots for the kilograms, has 

 bSen given to Messrs. Johnson, Matthe^', & 

 Co., of Loudon. This house agrees to furnish 

 thirtj' bars, X -shaped, and further specified 

 as follows : the length to be 1.20 metres ; the 

 densitj', not less than 21.5; the alloy to be 

 such, that, in 100 parts, there shall be not less 

 than 89.75 nor more than 90.25 parts of plati- 

 num, and not less than 9.75 nor more than 

 10.25 of iridium, witli a tolerance of 0.1 iron, 

 0.1 ruthenium, 0.15 rhodium and palladium, 



