868 



SCIENCE. 



[N. S. Vol. XIV. No. 362. 



The publication of this research added 

 much to Eowland's rapidly growing repu- 

 tation, and because of that fact, as well as 

 on account of its intrinsic value, it is im- 

 portant to note that his conclusions have 

 been held in question, with varying degrees 

 of confidence, from the day of their an- 

 nouncement to the present. The experi- 

 ment is one of great difficulty and the effect 

 to be looked for is very small, and there- 

 fore likely to be lost among unrecognized 

 instrumental and observational errors. It 

 was characteristic of Rowland's genius that 

 with comparatively crude apparatus he got 

 at the truth of the thing in the very start. 

 Others who have attempted to repeat his 

 work have not been uniformly successful, 

 some of them obtaining a wholly negative 

 result, even when using apparatus appar- 

 ently more complete and effective than 

 that first employed by Rowland. 



Such was the experience of Lecher in 

 1884, but in 1888 Roentgen confirmed Row- 

 land's experiments, detecting the existence 

 of the alleged effect. The result seeming 

 to be in doubt, Rowland himself, assisted 

 by Hutchinson, in 1889, took it up again, 

 using essentially his original method, but 

 employing more elaborate and sensitive ap- 

 paratus. They not only confirmed the early 

 experiments, but were able to show that the 

 results were in tolerably close agreement 

 with computed values. The repetition of 

 the experiment by Himstedt in the same 

 year resulted in the same way, but in 1897 

 the genuineness of the phenomenon was 

 again called in question by a series of ex- 

 periments made at the suggestion of Lipp- 

 man, who had proposed a study of the re- 

 ciprocal of the Rowland effect, according to 

 which variations of a magnetic field should 

 produce a movement of an electrostatically 

 charged body. This investigation, carried 

 out by Cremieu, gave an absolutely nega- 

 tive result, and because the method was en- 

 tirely different from that employed by Row- 



land and, therefore, unlikely to be subject 

 to the same systematic errors, it naturally 

 had much weight with those who doubted 

 his original conclusions. 



Realizing the necessity for additional ev- 

 idence in corroboration of his views, in the 

 fall of the year 1900 the problem was again 

 attacked in his own laboratory, and he had 

 the satisfaction, only a short time before his 

 death, of seeing a complete confirmation of 

 the results he had announced a quarter of 

 a century earlier, concerning which, how- 

 ever, there had never been the slightest 

 doubt in his own mind. It is a further 

 satisfaction to his friends to know that a 

 very recent investigation at the Jefferson 

 Physical Laboratory of Harvard University, 

 in which Rowland's methods were modified 

 80 as to meet effectively the objections made 

 by his critics, has resulted in a complete 

 verification of his conclusions. 



On his return from Europe, in 1876, his 

 time was much occupied with the beginning 

 of the active duties of his professorship, and 

 especially in putting in order the equipment 

 of the laboratory over which he was to pre- 

 side, much of which he had ordered while 

 in Europe. In its arrangement great (many 

 of his friends thought undue) prominence 

 was given to the workshop, its machinery, 

 tools, and especially the men who were to 

 be employed in it. He planned wisely, 

 however, for he meant to see to it that 

 much, perhaps most, of the work under his 

 direction should be in the nature of original 

 investigation, for the successful execution 

 of which a well manned and equipped work- 

 shop is worth more than a storehouse of 

 apparatus already designed and used by 

 others. 



He shortly found leisure, however, to 

 plan an elaborate research upon the me- 

 chanical equivalent of heat, and to design 

 and supervise the construction of the nec- 

 essary apparatus for a determination of the 

 numerical value of this most important 



