1821.] 



Th» Royal Society of London- 



b5 



grand subjects of investigation; such 

 for instance, as the nature of the sys- 

 tems of the fixed stars, their chances, 

 the relations of coiiielary bodies to tlie 

 sun, and the motions of those meteors, 

 which in passing through our atmo- 

 sphere, tlirow down showers of stones : 

 for. it cannot be doubted, that these 

 bodies belong to the heavens, and tliat 

 they are not fortuitous or atmospheric 

 formations ; and in a system, which is 

 all harmony, they must be g verned by 

 fixed Lnvs, and intended for definite 

 purposes. 



The grand question of universal 

 gravitation, and its connexion with the 

 figure of the earth, has been long 

 solved ; but the mechanical refinements 

 of one of <nir Fellows have aifbrded 

 means of estimating with more perfect 

 exactness the force of gravity ; — and 

 that pendulum wliicli is so well fitted 

 as a standard of measure, may he ad- 

 mirably applied to acquaint us with (he 

 physical constitution of the surface of 

 the earth. I trust we shall have some 

 interesting new experiments on this 

 subject. Our brethren of the Royal 

 Academy of Sciences of Paris, who 

 liave laboured with so much zeal and 

 activity towards the measurement of a 

 great arc of the meridian in Fiance and 

 Spain, are, I know, extremely desirous 

 their measures should be connected 

 with those carried on by the command 

 o^ the Board of Ordnance in Britain; 

 that the work should be completed by 

 the philosophers of btith countries. 

 Should this be done, there will be 

 established, on the highest authority, 

 an admeasurement of nearly twenty 

 d^rees, or l-18th of (he whole cir- 

 cumference of the earth, from the Shet- 

 land Islands to Formentera, which will 

 be a great record for posterity, and an 

 honour for our own times. 



I cannot pass over the subject of the 

 figureof the earth, continued Sir Hum- 

 phrey, without referring to the late 

 voyage to the Arctic Uegions, which 

 has shewn that there is an accessible sea 

 to (lie west of Baflin's Bay, presenting 

 hopes of greater discoveries, and which 

 has terminated in a way equally honour- 

 able to those by whom the expedition 

 was planned, and to the brave, enter- 

 prising, and scientific navigators by 

 whom it was executed. Such expedi- 

 tions are wordiy the greatest maritime 

 nation of the world ; shewing, that her 

 resources are not merely employed for 

 gaining power or empire, but likewise, 

 for what men of science must consider 



as nobler pur poses, in attempting disco- 

 veries which have the common benefit 

 of mankind for their object, and the 

 extension of the boundaries of science. 



In the theory of light and vision, 

 the discoveries of Huygens, Newton, 

 and Wo'laston, have been followed by 

 those of Malus ; and the new pliEeno- 

 mena of polarization, which we owe 

 to tlie genius of that excellent and 

 much-to-be-lamented philosopher, are 

 constantly leading to new discoveries : 

 and notwithstanding the imjiortant la- 

 bours of Arago, Biot, Brewster, and 

 Herschei, the inquiry is not yet ex- 

 hausted ; and it is extremely pro- 

 bable that these beautiful results will 

 lead to a more profound knowledge 

 tlian has hitherto been obtained con- 

 cerning the intimate constiution of 

 bodies, iind eslablish a ne^v connexion 

 between mechanical and chemical phi- 

 losophy. 



The subject of heat, so nearly allied 

 to that of light, has lately afforded a 

 rich harvest of discovery, yet it is fertile 

 in unexplored phsenomena. The ques- 

 tion of the materiality of heat will 

 probably be solved at the same time as 

 that of the uudulatory hypothesis of 

 light, should the human mind ever be 

 capable of imderstanding the causes 

 of tliese mysterious phsenomena. The 

 applications of the doctrines of heat 

 to the atomic or corpuscular phi- 

 losophy of ciiemistry, abound in new 

 views ; and probably at no very (^stant 

 period these views will attain a precise 

 mathematical foim. There are many 

 remarkable circumstances which seem 

 to point to some general law on the 

 subject. First, — the apparent equable 

 motion of radiant matter, or light and 

 heat, through space : — 2. The equable 

 expansion of all elastic fluids by equal 

 increments of temperature: — 3. The 

 contraction or expansion of gases by 

 chemical changes, in some direct ratio 

 to their original volume ; for instance, 

 ^ or \ : — 4. The circumstance that tlie 

 elementary particles of all bodies ap- 

 pear to possess the same quantity of 

 heat. 



In electricity the wonderful instru- 

 ment of Volta has done more for the 

 obscure parts of physic and chemistry, 

 than the microscope ever effected for 

 natural history, or even the telescope 

 for astronomy. After presenting to us 

 the most extraordinary and unexpected 

 results in chemical analysis, it is now 

 throwing a new light upon magnetism : 

 Magnos ncoinotws in usus. 



But 



