Sept. 14, 1876] 



NATURE 



427 



of Captain Sigsbee, who followed with like fervour and 

 resolution, and made further improvements in the apparatus 

 by which he has done marvels of easy, quick, and sure deep- 

 sea sounding in his little surveying ship Blake; and of the 

 admirable official spirit which makes such men and such doings 

 possible in the United States Naval Service. I would like 

 to tell you too of my reason for confidently expecting that 

 American hydrography will soon supply the data from tidal 

 observations, long ago asked of our Government in vain by a 

 Committee of the British Association, by which the amount of 

 the earth's elastic yielding to the distorting influence of the sun 

 and moon will be measured ; and of my strong hope that the 

 Compass Department of the American Navy will repay the 

 debt to France, England, and Germany so appreciatively acknow- 

 ledged in their reprint of the works of Poisson, Any, Archibald 

 Smith, Evans, and the Liverpool Compass Committee, by giving 

 in return a fresh marine survey of terrestrial magnetism, to 

 supply the navigator with data for correcting his compass without 

 sights of sun or stars. 



Can I go on to precession and nutation without a word of 

 what I saw in the Great Exhibition of Philadelphia? In the 

 U.S. Government part of it. Prof. Hilgard showed me the 

 measuring-rods of the U.S. Coast Survey, with their beautiful 

 mechanical appliances for end measurement, by which the three 

 great base Imes of Maine, Long Island, and Georgia, were 

 measured with about the same accuracy as the most accurate 

 scientific measurers, whether of Europe or America, have at- 

 tained in comparing two metre or yard measures. 



In the United States telegraphic department I saw and heard 

 Eli>ha Gray's splendidly worked-out electric telephone actually 

 sounding four messages simultaneously on the Morse code, and 

 clearly capable of doing yet four times as many with very mode- 

 rate improvements of detail ; and I saw Edison's automatic 

 telegraph delivering 1,015 words in 57 seconds : this done by 

 the long-neglected electro-chemical method of Bain, long ago 

 condemned in England to the helot work of recording from a 

 relay, and then turned adrift as needlessly delicate for that. In 

 the Canadian department I heard "To be or not to be, ... . 

 there's the rub, " through an electric telegraph wire ; but, scorn- 

 ing monosyllables, the electric articulation rose to higher flights, 

 and gave me passages taken at random from the New York 

 newspapers: — "S.S. Cox has arrived" (I failed to make out 

 the S.S. Cox) ; " I'he City of New York," " Senator Morton," 

 ' ' The Senate has resolved to print a thousand extra copies ;" 

 *' The Americans in London have resolved to celebrate the 

 coming 4th of July." All this my own ears heard, spoken to 

 me with unmistakable distinctness by the thin circular disc arma- 

 ture of just such another little electro-magnet as this which I 

 hold in my hand. The words were shouted with a clear and 

 loud voice by my colleague-judge. Prof Watson, at the far end 

 of the tel^raph wire, holding his mouth close to a stretched 

 membrane, such as you see before you here, carrying a little 

 piece of soft iron, which was thus made to perform in the neigh- 

 bourhood of an electro-magnet in circuit with the line motions 

 proportional to the sonorific motions of the air. This, the 

 greatest by far of all the marvels of the electric telegraph, is 

 due to a young countryman of our own, Mr. Graham Bell, of 

 Edinburgh and Montreal, and Boston, now becoming a natu- 

 ralised citizen of the United States. Who can but admire the 

 hardihood of invention which devised such very slight means to 

 realise the mathematical conception that, if electricity is to 

 convey all the delicacies of quality which distinguish articulate 

 speech, the strength of its current must vary continuously and as 

 nearly as may be in simple proportion to the velocity of a particle 

 of air engaged in constituting the sound ? 



The Patent Museum of Washington, an institution of which 

 the nation is justly proud, and the beneficent working of the 

 United States patent laws, deserve notice in the section of the 

 British Association concerned with branches of science to which 

 nine-tenths of all the useful patents of the world owe their foun- 

 dations. I was much struck with the prevalence of patented 

 inventions in the Exhibition : it seemed to me that every good 

 thing deserving a patent was patented. I asked one inventor of 

 a very good invention "Why don't you patent it in England?" 

 He answered, "The conditions in England are too onerous." 

 W^e certainly are far behind America's wisdom in this respect. 

 If Europe does not amend its patent laws (England in the oppo- 

 site direction to that proposed in the BUls before the last two 

 sessions of Parliament) America will speedily become the nursery 

 of useful inventions for the world. 



I should tell you also of "Old Prob's " weather warnings. 



which cost the nation 250, cxx) dollars a year ; money well spent 

 say the western farmers, and not they alone : in this the whole 

 people of the United States are agreed, and though Democrats 

 or Republicans playing the "economical ticket " may for half a 

 session stop the appropriations for even the United States Coast 

 Survey, no one would for a moment think of proposing to starve 

 " Old Prob ; " and now that 80 per cent, of his probabilities have 

 proved true, and General Myers has for a month back ceased to 

 call his daily forecasts ' ' probabilities " and has begun to call 

 them indications, what will the western farmers caU him this 

 time next year? 



And the United States Naval Observatory, full of the very 

 highest science, under the command of Admiral Davis ! If, 

 to get on to precession and nutation, I had resolved to omit 

 telling you that I had there, in an instrument for measuring 

 photographs of the transit of Venus — shown me by Prof. Hark- 

 ness, a young Scotsman attracted into the United States Naval 

 Service — seen for the first time in an astronomical observatory a 

 geometrical slide, the verdict on the disaster on board the 

 Thunderer, published while I am writing this address, forbids 

 me to keep any such resolution, and compels me to put the ques- 

 tion, Is there in the British Navy, or in a British steamer, or in 

 a British land boiler another safety-valve so constructed that by 

 any possibility, at any temperature, or under any stress it can 

 jam ? and to say that if there is it must be instantly corrected or 

 removed. 



I ought to speak to you, too, of the already venerable Harvard 

 University, the Cambridge of America, and of the Technological 

 Institute of Boston, created by William Rogers, brother of my 

 late colleague in this university (Glasgow), Henry Rogers, and 

 of the Johns Hopkins University of Baltimore, which with its 

 youthfid vigour has torn Sylvester from us, has utilised the 

 genius and working power of Roland for experimental research, 

 and three days after my arrival in America, sent for the young 

 Porter Poinier to make him a Fellow. But he was on his death- 

 bed in New York ' ' begging bis physicians to keep him alive just 

 to finish his book, and then he would be willing to go." Of his 

 book, "Thermodynamics," we may hope to see at least a part, 

 for much of the manuscript, and good and able friends to edit it, 

 are left ; but the appointment to a Pellowship in the Johns 

 Hopkins University came a day too late to gratify his noble am- 

 bition. 



But the stimulus of intercourse with American scientific men 

 left no place in my mind for framing, or attempting to frame 

 a report on American science. Disturbed by Newcomb's sus- 

 picions of the earth's irregularities as a Time-keeper, I could 

 think of nothing but precession and nutation, and tides and mon- 

 soons, and settlements of the equatorial regions, and melting of 

 polar ice. Week after week passed before I could put down 

 two words which I could read to you here to-day : and so I 

 have nothing to offer you for my Address but — 



Review of Evidence regarding Physical Condition of the Earth ; 

 its Internal Temperature ; the Fluidity or Solidity of its In- 

 terior Substance ; the Rigidity, Elasticity, Plasticity^ of its 

 External Figure ; and the Permanence or Variability of its 

 Period and Axis of Rotation. 



The evidence of a high internal temperature is too well known 

 to need any quotation of particulars at present. Suffice it to say 

 that below the uppermost ten metres stratum of rock or soil 

 sensibly affected by diurnal and annual variations of tempera- 

 ture, there is generally found a gradual increase of temperature 

 downwards, approximating roughly, in ordinary localities, 

 to an average rate of 1° C. per thirty metres of descent, but 

 much greater in the neighbourhood of active volcanoes, and 

 certain other special localities of comparatively small area, where 

 hot springs and, perhaps, also, sulphurous vapours prove an 

 intimate relationship to volcanic quality. It is worthy of remark 

 in passing, that, so far as we know at present, there are no 

 localities of exceptionally small rate of augmentation of under- 

 ground temperature, and none where temperature diminishes at 

 any time through any considerable depth downwards below 

 the stratum sensibly influenced by summer heat and winter cold. 

 Any considerable area of the earth of, say, not less than a kilo- 

 metre in any horizontal diameter, which for several thousand 

 years had been covered by snow or ice, and from which the ice 

 had melted away and left an average surface temperature of 

 13*, would during nine hundred years, show a decreasing tem- 

 perature for some depth down from the surface : and thirty- 

 six hundred years after the clearing away of the ice would still 

 show residual effect of the ancient cold, in a half rate of augmen- 



