1869.] Mathematical and Phi/sical Science. 591 



earth. But the chief experiments had been tried in a well made 

 many years ago at Kentish Town by a company formed for the 

 purpose of supj)lying the district with water. The total depth in 

 this instance was 1082 feet, 540 feet of which consisted of a bricked 

 wall, and the remainder of a boring lined with thin sheet iron. The 

 committee had obtained the use of the old well, and fitted up wind- 

 ing apparatus above it in a hut, to let specially-constructed ther- 

 mometers up and down in the boring. The general result of the 

 experiments was to prove an increase of temperature of one degree 

 for every 52 '4 feet increase in depth. 



Dr. J. H. Gladstone gave an address on the Eelation between 

 the Eefractive Energies and the Combining Proportions of the 

 Metals. He pointed out that in most cases, but not all, the less 

 the combining proportion of the metal, the greater is the refractive 

 energy. The rule just mentioned does not hold at all with non- 

 metallic elements, and proves most accurate with those metals which 

 form good definite salts, such as magnesium, u'on, and zinc. 



Professor Gustav Magnus read a paper on the Eeflection of 

 Heat, in which he made known a discovery of his own, that fluor- 

 spar has the property of reflecting, very largely, the dark invisible 

 rays emitted by hot rock-salt. There is much evidence tending to 

 prove that the heat-rays from rock-salt are of very great wave 

 length, belonging almost to one of the extremities of the spectrum. 



Lieut.-Colonel Strange, F.E.S., then spoke of the proceedings 

 last year at Norwich, which resulted in the formation of a committee 

 to determine whether there is adequate provision in Great Britain 

 for the vigorous prosecution of scientific research. The committee 

 had come unanimously to the conclusion that science had not ade- 

 quate means for its vigorous prosecution. They submit, as the 

 substance of their report, the recommendation that the full influ- 

 ence of the British Association for the Advancement of Science 

 should at once be exerted to obtain the appointment of a Eoyal 

 Commission to consider : — 1 . The character and value of existing 

 institutions and facilities for scientific investigation, and the amount 

 of time and money devoted to such pm-poses. 2. What modifica- 

 tions or augmentations of the means and facilities that are at pre- 

 sent available for the maintenance and extension of science are 

 requisite. 3. In what manner these can be best supphed. 



Mr. J. P. Gassiot called attention to a curious dark deposit in 

 certain vacuum tubes. 



On Saturday the papers were almost wholly mathematical. On 

 Monday the proceedings opened by the reading of several reports 

 of committees. Admiral Sir E. Belcher read the report of a com- 

 mittee appointed to apply to the Admiralty for aid in observing 



