250 



SCIENCE. 



[Vol. II., No. 29. 



and make lis respected by the nations of the world. 

 Such a prophecy may seem rash with regard to a nation 

 wliich does not yet do enough physical work to sup- 

 port a physical journal. But we know the speed with 

 which we advance in this country : we see cities 

 springing up in a night, and other wonders performed 

 at an unprecedented rate. And now we see physical 

 laboratories being built, we see a great demand for 

 thoroughly trained physicists, who have not shirked 

 their mathematics, both as professors and in so-called 

 practical life ; and perhaps we have the feeling, com- 

 mon to all true Americans, that our country is going 

 forward to a glorious future, when we shall lead the 

 world in the strife for intellectual prizes as we now 

 do in the strife for wealth. 



But if this is to be so, we must not aim low. The 

 problems of the universe cannot be solved without 

 labor: they cannot be attacked without the proper 

 intellectual as well as physical tools; and no physicist 

 need expect to go far without his mathematics. No 

 one expects a horse to win in a great and long race 

 who has not been properly trained; and it would be 

 folly to attempt to win with one, however pure his 

 blood and high his pedigree, without it. Th'e prob- 

 lems we solve are more difficult than any race: the 

 highest intellect cannot hope to succeed without prop- 

 er preparation. The great prizes are reserved for the 

 greatest efforts of the greatest intellects, who have 

 kept their mental eye bright and flesh hard by con- 

 stant exercise. Apparatus can be bought with money, 

 talents may come to us at birth ; but our mental tools, 

 our mathera.atics, our experimental ability, our knowl- 

 edge of what others have done before us, all have to 

 be obtained by work. The time is almost past, even 

 In our own country, when thiril-rate men can find a 

 place as teachers, because they are unfit for every thing 

 else. We wish to see brains and learning, combined 

 with energy and immense working-power, in the pro- 

 fessor's chair; but, above all, we wish to see that high 

 ■ and chivalrous spirit which causes one to pursue his 

 idea in spite of all difficulties, to work at the problems 

 of nature with the approval of his own conscience, 

 and not of men before him. Let him fit himself for 

 the struggle with all the weapons which mathemat- 

 ics and the expeiience of those gone before him 

 can fnrnish, and let him enter the arena with the 

 fixed and stern purpose to conquer. Let him not 

 he contented to stantj back with the crowd of medi- 

 ocrity, but let him press forward for a front place in 

 the strife. 



The whole universe is before us to study. The 

 greatest labor of the greatest minds has only given 

 us a few pearls; and yet the limitless ocean, with its 

 hidden depths filled with diamonds and precious 

 stones, is before us. The problem of the universe is 

 yet unsolved, and the mystery involved in one sin- 

 gle atom yet eludes us. The field of research only 

 opens wider and wider as we advance, and our 

 minds are lost in wonder and astonishment at the 

 grandeur and beauty unfolded before us. Shall we 

 help in this grand work, or not? Shall our country 

 do its share, or shall it still live in the almshouse of 

 the world f 



PAPERS READ BEFORE SECTION B. 



Determination of the relation between the im- 

 perial yard and the metre of the archives. 



BY WILLIAM A. ROGERS OF CAMBBIDGE, MASS. 



This paper was a continuation of one upon the 

 same subject presented at the Montreal meeting. 

 The mean result of the determinations up to that 

 time was as follows: Imperial yard + 3.37015 inches 

 = Metre des archives. 



The writer stated at that time, that he should not 

 like to be held to a very strict account with regard to 

 the last decimal figure, or even the last two decimal 

 figures, on account of the difficulty of obtaining the 

 requisite data. 



Since the meeting last year, additional data have 

 been obtained. In February of the present year, a 

 combined yard and metre was received from Paris. 

 The yard was compared with the imperial yard, in 

 1880, by Mr. Chaney, the warden 'of the imperial 

 standards. During the interval between 1880 ami 

 February of the present year, this metre has received 

 repealed comparisons with the metre of the Inter- 

 national bureau, under the direction of Dr. Fernet. 

 According to his report, this metre is 310 mikrons 

 too short at 0° centigrade; for the same temperature, 

 the yard was found by Mr. Chaney to be 20.7 mikrons 

 too short. 



Comparing the metre and the yard upon this bar 

 with the bronze yard and metre described at Mont- 

 real, and combining the results with those previously 

 found, the relation was found as follows: Imperial 

 yard -|- 3.37039 inches = Metre des archives. 



The magnetophone, or the modification of the 

 magnetic field by the rotation of a perfo- 

 rated metallic disk.i 



BY PKOF. H. S. CAKHAKT OF EVASSTON, ILL. 



The experiments of Bell, Preece, and others, on 

 the radiaphone, suggested the possibility of interrupt- 

 ing, or at least periodically modifying, the lines of 

 force proceeding from the poles of a magnet, by 

 means of a disk of sheet-iron, perforated with a .series 

 of equidistant holes, and rotated so that the holes 

 should pass directly in front of the magnetic pole. 

 It is well known that the armature placed on the 

 poles of a permanent magnet diminishes the strength 

 of the external field of force by furnishing superior 

 facilities for the formation of polarized chains of 

 particles from pole to pole. This is the case even 

 when the armature does not touch the poles, but is 

 in close proximity to them. 



If a piece of sheet-iron be placed over the poles 

 of a magnet without touching, and magnetic curves 

 he developed on paper above the iron, they will he 

 found to exhibit less intense and less sharply defined 

 magnetic action than when the sheet-iron is removed. 

 If, however, a sm.all hole be drilled directly over each 

 magnetic pole, the screening action of the sheet-iron 

 is modified in much the same way as when a hole is 



1 This paper will shortly be published in Science in full. 



