Letter from Charles S. Peirce to Carlile P. Patterson
(Paris, 02.06.1880)



 
Spanish translation & annotations
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Care Messrs. John Munroe & Co
7 Rue Scribe, Paris, France

Paris
June 2, 1880

 

Sr. C. P. Patterson
Superintendent

Dear Sir,

I have made experiments on the flexure of the Biot support, but I cannot exactly restore it to its original state and it is now stiffer than I had supposed. I first went to Faye and told him that the result of my experiments differed from the figures hitherto given by Borda, Biot, and Sabine by comparison with London; and that I wished to investigate the cause of this large discrepancy (far surpassing all ordinary and known sources of error) and to repeat the experiments if necessary. He kindly spoke to Admiral Mouchez and the latter wrote to me to say that the resources of the observatory were at my disposition. I then said that I should like to swing a pendulum on Biot's support


and to begin by testing its stiffness. That I got leave to do & I then had the necessary apparatus made.

As there was a prospect of some delay in getting the apparatus, and also because the International commission on the metre were making weighings in the hall at the observatory where I wished to work, I thought I could profitably go to Kew and reconnoitre. I therefore went over to England, though I had at the time a bronchitis which I had had since before I left Baltimore where I was confined to my room with it for several weeks. It had hung on ever since & when I reached England it was so cold there that I was made downright ill at once and the doctor advised my immediate return to France. So I did return and the English journey was useless. I then got hold of a French physician who treated me with hypophosphite of soda which had a wonderful effect so that I am now entirely free with my cough, which I really did not


hope ever to be.

Having got my apparatus for measuring the flexure up I found the shelf upon which Biot’s experiments were made so stiff that no flexure hardly could be detected. I then found upon inquiry that somebody whose name now escapes me had been making experiments on this stand since Biot's time and had added the two side braces shown in the figure.



I removed the screws which attach these side braces to the shelf and by wedging in pieces of wood succeeded in springing them away from the shelf and then got good measures of the flexure. Still, the shelf was remarkably stiff. On considering why it should be so, it became evident that it all depended on the firmness with which the iron shelf is screwed to the two brackets which support it, at the points A and B. Further examination showed me that the piece which is screwed into the middle of the shelf to support the pendulum could not

 
be the one which Biot had used. After some rummaging I found the one he had used. This one has four light small and nickely-looking screw feet. But it has also two thumb-screws to bind it down to the shelf.  These two screws are fore and aft not at the sides as they should be. These screws passed through holes in the plate forming the shelf into which iron plugs have since been put. (Why, one does not see.) It is therefore plain that the shelf has been taken up, the screws A, B have been removed & probably replaced stiffer than before. No doubt there would be some flexure about the piece on which the pendulum rested; but that would depend on how tightly it was screwed to the plate. On the whole the flexure of Biot's apparatus seems a datum hard to recover, though I do not yet quite despair of it.

It appears to me that the experiments I am now making are likely to leave the matter thus. Gravity has been three directly measured in Paris and it has also been determined by


 
the transportation of pendulums to London & Berlin.

Of the direct measures, Borda's positively requires a correction which brings it into semi-tolerable accord with mine. Biot's is subject to an uncertain correction in the same direction.

The comparison with Bessel's value is bad anyway. The comparison with Kater's is also bad but corrections being applied to it and to Kater’s value in London, a result approximating to mine is obtained.

I think it is clearly necessary to re-determine gravity in Paris in a manner which shall leave no possible doubt of the accuracy of the result & I am maturing a plan for this purpose.

Yours respectufully,

C. S. Peirce
Assist.

 

P. S. The work upon my papers is in active progress, but I absolutely need the results of Mr. Farquhar's swings on different supports at York. I hope it will come soon.

 

Transcription by Max Fisch, revised by Sara Barrena (2018)
Una de las ventajas de los textos en formato electrónico respecto de los textos impresos es que pueden corregirse con gran facilidad mediante la colaboración activa de los lectores que adviertan erratas, errores o simplemente mejores transcripciones. En este sentido agradeceríamos que se enviaran todas las sugerencias y correcciones a sbarrena@unav.es
Proyecto de investigación "The Cosmopolitan Peirce: Cartas de C. S. Peirce en su cuarto viaje europeo (abril-agosto 1880)"

Fecha del documento: 6 de septiembre 2018
Última actualización: 20 de septiembre 2018
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