r 1 o 



NA TURE 



[September 20, 1906 



temperatures depends on the particular kind of glass 

 employed. 



For many years thermometers have been verified at Kew 

 Observatory in large numbers annually, their indications 

 being referred to the Kew Scale of temperature. It has 

 recently become a matter of interest to determine to what 

 degree of accuracy the Kew Scale may be considered as 

 identical with that of the hydrogen thermometer, and this 

 memoir gives an account of some experiments undertaken 

 at the National Physical Laboratory with a view to 

 elucidate this question. 



The usual type of Kew standard thermometer is an instru- 

 ment having a range from below 32° to above 212° F., and 

 is usually divided only to 1° F. 



For the purpose of this research it was thought desirable, 

 after studying the behaviour of a number of these old 

 thermometers, to construct new standards, having a more 

 open scale and capable of being read to higher accuracy, 

 and to treat these from the beginning in a definite and 

 systematic manner. 



The readings of a Kew standard are always understood 

 to apply to the thermometer in a vertical position when 

 immersed in water up to the reading, and the instruments 

 are always intended to be used as " fixed " rather than as 

 " movable zero " instruments. That is, the normal pro- 

 cedure to measure any temperature on the Kew scale would 

 be first to determine the zero and afterwards the tempera- 

 ture in question, applying to the latter a constant correc- 

 tion for any deviation of the zero point from its nominal 

 correct value, 0° C. or 32° F., and ignoring all subsequent 

 zero changes. 



The main conclusions of the work are : — 



(i) The departure of the natural scale of the " Kew " 

 mercury-in-glass thermometer from the international 

 hydrogen scale is very small at all temperatures. 



(2) For measurement of temperature differences over 

 ordinary ranges, such as in calorimetry, the results obtained 

 directly or indirectly from a Kew standard may be con- 

 sidered as hydrogen temperatures without application of 

 any correction. 



(3) In some instances when defining the temperature at 

 which certain standards have their definite value, such as, 

 for example, the temperature 62° F. for the British standard 

 yard, the temperature scale to which the measurement re- 

 ferred was not definitely specified. This research renders 

 it probable that if the instrument were a good English 

 glass thermometer approximating to a Kew standard, the 

 error made in considering its indications as identical with 

 the hydrogen scale would be within the limits of accuracy 

 of length measurements. 



(4) For the ordinary ranges of meteorological and clinical 

 thermometers reading to o°-i F., many thousands of which 

 have been verified at Kew annually for many years past, 

 the temperatures as given on the Kew certificate may be 

 considered as hydrogen temperatures. 



(5) The table appended gives the mean departure from 

 the hydrogen scale of the " Kew " scale of temperature as 



observed in this investigation, the figures being rounded to 

 the most probable o°.oo5 C. For comparison purposes the 



NO. 1925, VOL. 74] 



figures for French "Verre Dur" and for "Jena 

 Glass 16'" " are added in parallel columns, it being under- 

 stood that each glass is treated in the manner prescribed 

 for it, the Kew glass being a " fixed zero " scale and the 

 other two " movable zero." 



Paris. 

 Academy of Sciences, September 10. — M. A. Chauveau 

 in the chair. — Variations in the gravitation constant in the 

 Siniplon Tunnel : Marcel Brillouin. A resume of the 

 various corrections required by the crude readings of the 

 instrument used. The complete work will be published in 

 the Recticil des Savants ctrangcrs. — The experiments of 

 M. Villard and his theory of the aurora borealis : Carl 

 Stormer. In his memoir published in 1904 on the motion 

 of a material point carrying a charge of electricity, and 

 continued in two recent notes in the Comptes rendus, the 

 author has developed a theory which not only explains the 

 phenomena experimentally observed by M. Villard, but also 

 predicts others not yet observed, and renders doubtful 

 certain of M. V'illard's conclusions regarding the aurora 

 borealis. The experiment of M. Villard, in which the 

 magnetic field is due to two equal and opposite magnetic 

 poles, is considered in detail in the present note, and the 

 trajectories worked out for several cases, diagrams being 

 given. The author draws the conclusion that Birkeland's 

 theory is not shaken by M. Villard's paper. — The atomic 

 weight of silver : P. A. Guye and G. Ter-Gazarain. 

 Reasons are given for showing that the atomic weight of 

 silver should be lowered from 107-93 '° 107-89. — A case of 

 formation of anthocyanine under the influence of the punc- 

 ture of an insect (Eurrhipara urticata) : Marcel Mirande. 



CONTENTS. PAGE 



A Text-Book of Optics 509 



Researches in Japanese Waters. liy L. A. B. . . 510 



Bird Books for Beginners 511 



A Guide to British Diptera. By E. E. A 512 



Our Book Shelf: — 



Price: "Illogical Geology. The Weakest Point in 



the Evolution Theory."— G. A. J. C 513 



Robinson: " The Religion of Nature" 513 



Gherardi : " Carboni fossili inglesi " 514 



Fox : " How to Find and Name Wild Flowers'' . . 514 

 Letters to the Editor: — 



American Chemists and the Jubilee of the Coal-tar 



Colour Industry.— Prof. R. Meldola, F.R.S. . , 514 

 Horizontal Pendulums and Earthquake Echoes. — Dr. 



C. Coleridge Farr ; Prof. John Milne, F.R.S. 515 



Remarkable Rainbow Phenomena, — M. Spence , 516 

 The Mixed Transformation of Lagrange's Equations. 



Dr. E. J. Routh, F.R.S 516 



The Recent Controversy on Radium. By F. Soddy 516 



The Mysteries of Lhasa. (Illustrated.) 518 



Mining Geology. {Illustrated.) 520 



Notes 521 



Our Astronomical Column :— 



Jupiter's Sixth Satellite 524 



Holmes's Comet (1906/") 525 



Observations of Solar Phenomena, igo6 525 



Observations of Jupiter 5^5 



The Kodaikanal Observatory 5^5 



Chemistry at the British Association 525 



The Physical Geography of Volcanoes. {Illustrated.) 



By Dr. Tempest Anderson 527 



The Ascent of Ruwenzori 528 



The Toronto Meeting of the British Medical 



Association. By Prof. R. T. Hewlett 529 



A Larch Sawfly in Cumberland. By F. V. T. . . . 529 



Some Recent Paleeontological Papers 530 



University and Educational Intelligence 530 



Societies and Academies 531 



