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Dear Sir, In reply to yours of the 25th I have to say that I shall need all of the money already allowed me -$ 3000 from January 1 to June 30- and several bills will be postponed till July. I regret that no more than the sum you name can be allowed for the ensuing year, but having been informed of it some months ago I shall be able to arrange to do the best with it. I could make use |
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of more to good purpose in getting superior results and more of them but as long as there is only that I have to do the work of completing the preparatory pendulum work as well as it can be done with that sum. Even at that, I don't think it will discredit the coast Survey.
Your remark about winding the chronometers at different hours is most valuable. I have been winding them all at 7:30 A.m. I have now directed to have two wound at 5 P. M., and I have no doubt that this will be a material improvement. These two times are the only ones in the day at which |
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I can be sure of getting them wound at precisely the same time each day; which is essential. I think however that this will be sufficient, as long as the station is so remote. I am much obliged to you for the suggestion. I have no doubt there is a barometric correction to a chronometer although I suspect it is not as great as that of a clock. I will have the barometer read twice a day & will afterwards investigate their correction. My problem which is that of ascertaining the rate of a chronometer without caring for its correction, differs considerably |
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from that of the longitude people which is to find its correction without caring for its rate further than is necessary for finding its correction. They wish to know the correction at the time of exchanging signals. They observe time as closely as possible before and after & if there is a probable error in a determination of time of 1/20 of a second, they get the correction in this way to about that degree of accuracy &, therefore, more than two chronometers are in my opinion mere waste in a longitude party, under ordinary circumstances. But it is quite different with
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me. I want to know the rate to about 1/10 second a day or even closer if possible. Observations taken only a fraction of a day apart will not give this, because the observations themselves cannot be made accurate enough. What I do is therefore to run 5 chronometers together which are compared every day, and oftener when the pendulum is swung. They are compared by the chronograph, without disturbing them. I then have five tables constructed one for each chronometer between the times of comparison on the supposition that each |
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of the others runs uniformly between the times of observation. Then as what happens generally is that a chronometer has a gradually changing rate with occasional sudden changes, the misbehaving one is easily detected and the mean of the others is used to get my rate during the time of swinging. This works most satisfactorily & is in my opinion the only satisfactory way without a most superior clock which remains for a long time in a very favorable situation & has its performance carefully studied over a long period.
I will next week send you a |
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specimen of the 5 tables which will give you a better idea of the use of them than I can give by a description.
I wrote to you I believe that I intended to mount, not my chronograph, but my peculiar pendulum relay on a brick support. I ultimately decided on a different plan. I have remounted the pendulum on an entirely different support. I now have it mounted in the Geneva vacuum chamber, although I do not mean just yet to swing in vacuo. This rests on two large iron bars extending from a large brick pier to a stone |
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wall & I am now having a peculiar brass arrangement made for securely holding the pendulum relay. Meantime, I am occupied with comparisons of the length of the pendulum, which have not yet been satisfactory in Hoboken. The reason is the radiation of heat. To prevent this I have ordered three mattresses made, to be stuffed with cat-tail, which is the best substance known, I believe, for this purpose. These will completely surround the pendulum stand with apertures for light. I shall freely use artificial light concentrated by lenses but with the heat rays cut off by a solution
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of alum in glass vessels made of plate glass cemented together with a mixture of rosin & beeswax.
I am getting good work on the gitter measurements. I have found a line Van der Willigen 16= Kirchhoff 1207.3 = Ariström 561.80 the deflection of which is almost exactly 45º so that with one change of the position of the circle, reading two microscopes, the whole circle is filled up and the errors of graduation are eliminated. The errors of graduation of the prominent line C which was first proposed by Maxwell, as Mr. Rutherford informs me, for this purpose, can |
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be eliminated by 14 changes of the position of the circle. If I use this it will take a great deal of work.
A doubt has arisen in my mind in regard to one of the usual corrections of these measurements; and I have a little apparatus constructing which will settle the question. I will say no more about it, at present, except that if it should turn out that the correction does not exist, it will have an important bearing on the theory of light; but it may be I am pursuing a phantom. Mr. Rutherford does not understand that the assistance he is to afford me goes beyond the diffraction measures but I shall perhaps succeed in interesting him in building up the |
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metre. To do so, I must get a totally different plan for doing this; and I have a vague idea of one which I shall perhaps be able to work up.
I had word this morning that my sister had lost her little boy Rogers 3 years old by diphtheria & her little girl is sick with it. She herself is just recovering from a severe illness. Yours very respectfully & truly C. S. Peirce P. S. I had word from Pickering that a broken window in the pendulum building in the Cambridge Observatory grounds was a source of danger to the observatory
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from fire & that he would like to have the building removed. I at once acknowledged & at the same time wrote to Eliot saying that I had received this letter & that the building would be removed if desired but that I should like to understand the wishes of the college in the matter. The particular reason mentioned could be met by wooden shutters properly secured, & that it would be desirable to reocuppy the station eventually, and therefore I should be glad to know whether the reason given was the only objection to the continuance of the pendulum station or whether it was desired that it be removed.
C. P. Patterson Esq. Supt U. S. Coast Survey Washington D. C.
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Transcription by Sara Barrena (2017)
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 "La correspondencia del tercer viaje europeo de Charles S. Peirce (septiembre-noviembre 1877)"
Fecha del documento: 1 de febrero 2017
Última actualización: 17 de agosto 2017
