150 FISCHER: LENGTH STANDARDS AND MEASUREMENTS 



meridian extending from the equator to the pole to be 5, 130,740 

 toises, from which it followed that the meter was slightly greater 

 than the one-half toise or 0.513074 toise. 



The actual construction of the new standards of length was 

 immediately begun. At first four brass end standard meters 

 were made, each very nearly equal to the computed length of the 

 meter. Then the bar which was found after several comparisons 

 to be nearest to the required length, was selected as the pro- 

 visional standard. Finally two platinum meters and twelve 

 iron meters were constructed and compared with the provisional 

 jneter and with one another by means of a comparing apparatus 

 which was capable of showing differences of 0.001 mm. Also, 

 the rates of expansion of all the meters were carefully deter- 

 mined between 0° and 32°C. The comparisons and adjustments 

 of the several meters were continued until no difference amount- 

 ing to more than 0.001 mm. could be found at the temperature of 

 melting ice. They were all consequently declared to be exact, 

 and one of the platinum meters, subsequently known as the meter 

 des Archives, from its place of deposit, was reserved as the new 

 prototype measure of length. 



The other platinum meter was deposited at the observatory 

 at Paris, while the iron meters were distributed amongst the 

 countries which had cooperated with France in this work. 



One of these iron bars was brought to the United States by 

 Ferdinand R. Hassler, who afterwards organized the U. S. 

 Coast Survey, or as it is now known, the Coast and Geodetic 

 Survey. 



I am not familiar with what Hassler's purpose was in coming to 

 the United States, but it hardly seems possible that he should have 

 brought, with him the standard of length upon which was based 

 all the early work done by the Survey, unless he had in mind the 

 organization of that service, and yet the fact that he presented 

 this standard to the American Philosophical Society of Phila- 

 delphia shortly after his arrival contradicts this view. When 

 Hassler was placed in charge of the Coast Survey, he secured 

 the bar from the Philosophical Society and it remained in the 

 possession of the Coast Survey until the organization of the 



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