Moll tests early standards for the kilogram

Schreiben des Herrn Professors und Ritters Moll aus Utrecht an den Herausgeber.

Utrecht 1831. Jan. 9.

During my stay in your vicinity this last summer, we had some conversation about the real value of the Kilogramme expressed in British Imperial Troy weight. You are aware that each of the Governments who sent Commissarys to the Comittee of weights and measures in Paris were presented with a Kilogramme and a meter, by the french Government, and that a similar present was made to each of the Commissioners. These weights and measures were fabricated under the eyes of the united Commission, and marked with their particular stamp, after being previously examined, it is said with great care. The Kilogramme, the meter of the late Mr. Van Swindel are now in my hands, as also that Copy of the old dutch Troy weight, on which the comparison of dutch Troy, and metric weight was made in Paris, by our Commissioners MM. Van Swinden et Aeneas with Mr. Lefevre Gineau. By means of a pair of scales and weights of Robinson, similar to yours, I have compared Van Swinden's Kilogramme and several standards of the same weight with the English Troy weights of Robinson, and I am very sorry to say that the result has left me in an entire darkness as to the real value of the Kilogramme. I need scarcely say, that in using the scales, I constantly employed Borda's method.

  British Imp.
Troy grains.

A mean of several experiments on Van Swinden's Kilog. gave 

15432,295 

A Kilogramme modele made by Fortin and belonging to Government. 

15432,752 

A Kilogramme modele made by Gandolfi, balancier de la monnaye de Paris, and sent during the french occupation of this country by the Parisian Mint-administration to the Mint at Utrecht.

15432,730 

Another Kilogramme by the same artist, and also belonging to the Mint of Utrecht.

15433,752 

One Kilogramme made by Nagel, balance maker at Amsterdam, and serving as standard in the Mint

15432,920 

Another one, made as a Standard for the Royal Institute of Holland.

15432,985

Another one, by the same in my possession

15433,420 

Another also said to be a standard

15434,91 

But Mr. Mathieu in the annuaire du Bureau des longitudes calculates the value of the Kilog. in British Imperial Troy

15488,355

And Mr. Kelly concludes from actual experiments on a Standard Kilogramme.

15433 

From all this I conclude that I am quite ignorant of the real value of the metrical weight.

M. M. Van Swinden, Aeneas and Lefevre Gineau compared in Paris, the identical Standard of the dutch Troy weight, now in my possession, with the original Kilog. They found the pound Dutch Troy aqual to 492,16772. I weighed, very repeatedly both the dutch Troy pound, and the Kilog. of Van Swinden in english Troy grains of Robinson, by these means I found the dutch Troy weight equal to 492,14908!!! I see no possibility of explaining this enormous difference but by supposing that the original Kilogramme, which they had in Paris, was different from Van Swinden's.

In order to acquire some additional evidence of the accuracy of Robinson's British Imperial Troy, I procured a copy of the Imperial Troy pound from Mr. Bate, who, as you well know, made the standards of the new British weights and measures. I found by several ponderations, the weight of the Mr. Bate's pound to be 5759,935 of Robinson's grains.

In 1818 the Administration of the Mint in this country obtained from the Administration of the English Mint in London, two copies of the British Troy pound = 5760 Grains, from His Majesty's Mint; I examined both copies, and one of them is actually in my possession. They are of unequal weight and very different from 5760 Grains of Robinson, or from Mr. Bate's Troy pounds. One of them kept in the Mint here weighs 5758,57 of Robinson's grains, the other in my possession 5758,40 gr.

I forgot to mention that the dutch pound Troy weighs 7594,975. You will, of course, observe that the Dutch pound Troy is of 16 oz.

Moll.

Astronomische Nachrichten, vol. 9, issue 6, columns 74-76 (1831).


Portrait of Moll

Gerrit (Gerrard) Moll (1785-1838) was a distinguished Dutch physicist. A good short biography can be found at

www.dwc.knaw.nl/wp-content/berkelbio/39.moll.pdf

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