Letter from Charles S. Peirce to his wife Melusina Fay
(Paris, 23.01.1876)

Spanish translation & annotations


Sunday 1876 Jan 23

My dearest Zina,

I am now excessively busy. I get up at 8 AM have breakfast & start as soon as possible for the observatory which it takes a half hour to reach in a cab. I can then not possibly perform a series of experiments in less than 5 hours under the happiest circumstances & generally it takes 6. Then I walk to Fayot's by the Luxembourg & wash my hands & dine & return very tired to my appartment where I take a nap and change my shirt


& then have a good deal to do in the evening. I am constantly in a state of fatigue.

Since you want to know about my business I will describe a series of experiments. The first thing is to level the instrument so as to have the agate level fore & aft then the pendulum is put on with gloved hands so as not to warm it. The room is always at about 40º F. The instrument is leveled so that the pendulum marks zero on the scale when at rest. Then the comparator which carries the microscope is leveled in two directions so as to have its axis of rotation vertical. Then the two microscopes are leveled. Then the standard is leveled in two directions. Then the instrument is left alone for ten minutes


to recover the temperature of the room. Then the distance between the knife-edges is measured. For this purpose the microscopes are turned on the standard & the mercurial thermometer is read & the metallic thermometer is read by 6 settings of the micrometer. Then I set 9 times on the end of the metre above & 9 times below. Then I take the metallic thermometer again & the mercurial. Then the comparator  with microscopes is set on the pendulum and each edge has to be observed 1st dark & 2nd illuminated, on two wires and 3 times each way making 12 settings on each edge. Lastly the metallic & mercurial thermometers are read & the first measure of the length of the



pendulum is complete. After that I set the pendulum going at an arc of 2º30' and when it reaches 2º20' I give the time to Farquhar. Then he has a table so that he gives me the precise moment when I am to read temperature, arc, & take transits. I observe transits when the arc is 2º, 1½º, 1º and ½º. That completed, the pendulum is stopped & the length measured again. It is then turned upside down and allowed 15 minutes to cool & measured again. Then started & observed the same as before. Then measured again. Then the centre of gravity is measured on a machine for the purpose in four positions. Then the knife-edges are carefully taken out & put in again another way for the next day.



Transcription by Max Fisch, revised by Sara Barrena (2014)
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 "Charles S. Peirce en Europa (1875-76): comunidad científica y correspondencia" (MCI: FFI2011-24340)

Fecha del documento: 3 de febrero 2014
Última actualización: 3 de febrero 2014

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