a:^ ture 



25 



THURSDAY, MAY 9, 1901. 



EARLY HISTORY OF THE THERMOMETER. 



Evolution of the Thermometer, 1592— 1743. By Henry 



Carrington Bolton. Pp. 98. (Easton, Pa., U.S.A. : 



Chemical Publishing Co., 1900.) Price i dollar. 

 'X'HIS is a most interesting little book, giving the 

 history of the thermometer from the time of 

 Galileo to that of Celsius and Christin. 



Galileo's first instrument is thus described in a letter 

 written by Father Castelli and dated 20th September, 

 1638, in which he says it was used in public lectures 35 

 years before. " Galileo took a glass vessel about the 

 size of a hen's egg, fitted to a tube the width of a straw 

 and about two spans long ; he heated the glass bulb in 

 his hands and turned the glass upside down so that the 

 tube dipped in water held in another vessel ; as soon as 

 the ball cooled down the water rose in the tube to the 

 height of a span above the level in the vessel ; this 

 instrument he used to investigate degrees of heat and 

 cold. ' 



According to Viviani, author of a " Life of Galileo," pub- 

 lished in 1 718, this instrument was invented about the 

 time he became professor of mathematics in Padua ; 

 this was towards the end of 1592. 



Sanctorius, a medical colleague of Galileo, appears to 

 have appreciated the value of fi.xed points for graduation, 

 and for this purpose he used snow and the heat of a 

 candle ; the range thus obtained he divided into degrees. 

 The thermometer was applied by him to take the tem- 

 perature of the human body ; in one instrument the bulb 

 was constructed so as to go into the patient's mouth. 



Sanctorius, in his " Commentaries on Galen,'' speaks of 

 the thermometer "as a most ancient instrument," and it 

 has been suggested by Cleveland Abbe that the instru- 

 ment was known before the time of Galileo and that his 

 work consisted in the addition of a scale. 



The first sealed thermometer was made some time 

 prior to 1654 by Ferdinand II., Grand Duke of Tuscany ; 

 he filled the bulb and part of the tube with alcohol, and 

 then sealed the tube by melting the glass tip. Ferdinand 

 and his brother, Leopold de Medici, promoted the 

 establishment in Florence of the Accademiadel Cimento, 

 and the accounts of their experiments, published in 1667 

 and translated into English by Waller in 1684, contain 

 •descriptions of various thermometers made and used by 

 the members. One of these old thermometers was 

 given by the Grand Duke of Tuscany to the late Prof. 

 Babbage. and is now in the Cavendish Laboratory at 

 Cambridge. 



In England about the same time Boyle made experi- 

 ments on thermometers. His " Lectures on Cold " were 

 published in 1665 in obedience to the command of the 

 Royal Society, " imposed on me in such a way that I 

 thought it would less misbecome me to obey it unskilfully 

 than not at all. Especially since from so illustrious a 

 company (where I have the happiness not to be hated) I 

 may, in my endeavours to obey and serve them, hope to 

 find my failings both pardoned and made occasions of 

 discovering the truths I aimed at." 



The second discourse of these lectures contains some 



NO. 1645, VOL. 64] 



" New Observations about the Deficiencies of Weather 

 Glasses, together with some considerations touching the 

 New or Hermetical Thermometers." 



Boyle felt the need of fi.xed points. Hooke, in his 

 " Micrographia," describes some thermometers with stems 

 above four feet long, in which the range between summer 

 and winter was nearly the length of the stem. To 

 graduate the stems he placed zero at the point where the 

 liquid stood when the bulb was in freezing distilled water ; 

 thus to him belongs the credit of taking the temperature 

 of the freezing point of water as the lower fixed point. 



There appears to be considerable doubt as to who 

 first employed mercury as the thermometric liquid ; the 

 Accademia del Cimento used such an instrument in 1657, 

 and they were known in Paris in 1659. Fahrenheit, 

 however, appears to have been the first to construct, in 

 1714, mercury thermometers having trustworthy scales. 



The use of the boiling point of water as the upper fixed 

 point was suggested by Carlo Renaldini in 1694, who 

 published, at the age of eighty years, a work on natural 

 philosophy. 



Sir Isaac Newton, in his " Scala Graduorum," published 

 in the Phil. Trans, in 1701, adopts linseed oil as the 

 thermometric liquid. He took as the fixed points the 

 melting point of ice and the temperature of the human 

 body, calling the one o' and the other 12'. On this scale 

 he gives as the boiling point of water 34^, and as the 

 melting point of lead 96". Newton did not adopt the 

 boiling point of water as a fixed point. 



After an interesting reference to Amontons and others 

 who worked at thermometry in the latter part of the 

 seventeenth century, Mr. Bolton describes the labours of 

 Fahrenheit, who was born in 1686. His work began in 

 1706. His skill as a glass worker was very great and 

 enabled him to carry out many designs. In his own 

 account of the instrument he says : " The scale of the 

 thermometers used for meteorological observations begins 

 below with 0° and ends with 96". The division of the 

 scale depends upon three fixed points, which are obtained 

 in the following manner. The first point below at the 

 beginning of the scale was found by a mixture of ice 

 water and sal ammoniac or also sea salt ; when a ther- 

 mometer is put in such a mixture the liquid falls until it 

 reaches a point designated as zero .... The second 

 point is obtained when water and ice are mixed without 

 the salts named ; when a thermometer is put into this 

 mixture the liquid stands at 32°, and this I call the 

 commencement of freezing .... The third point is 

 at 96^ The alcohol " — it is expressly stated earlier that 

 the thermometers were of two kinds, the one containing 

 alcohol, the other mercury — " expands to this height 

 when the thermometer is placed in the mouth or in the 

 armpit of a healthy man and held there until it acquires 

 the temperature of the body." 



Above this temperature the scale was merely lengthened 

 by dividing the tube into equal spaces ; one of the 

 divisions marked 212^ on a certain thermometer was 

 observed to coincide with the boiling point of water, thus 

 the division of the fundamental interval between the 

 freezing point and boiling point into iSo parts 'was 

 accidental. If we take these two temperatures as our 

 points of departure, marking them as 32" and 212°, the 

 normal temperature of the human body is 98°'4, not 96" 



C 



