20 



RBroRT — 1884. 



to elevate phrases above things : to refer, for example, to the principle 

 of the conservation of energy for an explanation of the persistent rotation 

 of a fly-wheel, almost in the style of tlie doctor in ' Le ^lalade Imaginaire,' 

 who explains the fact that opium sends you to sleep by its soporific 

 virtue. Maxwell's endeavour was always to keep the facts in the fore- 

 ground, and to his influence, in conjunction with that of Thomson and 

 Helmholtz, is largely due that elimination of unnecessary hypothesis 

 which is one of the distinguishing characteristics of the science of the 

 present day. 



In speaking unfavourably of superfluous hypothesis, let me not be 

 misunderstood. Science is nothing without generalisations. Detached 

 and ill-assorted facta are only raw rprterial, and in the absence of a 

 theoretical solvent, have but little nutritive value. At the present time 

 and in some departments, the accumulation of material is so rapid that 

 there is danger of indigestion. By a fiction us remarkable as any to be 

 found in law, what has once been published, even though it be in the 

 Russian language, is usually spoken of as 'known,' and it is often for- 

 gotten that the rediscovery in the library may be a more difficult and 

 uncertain process than the first discovery in the laboratory. In this 

 matter we are greatly dependent upon annual reports and abstracts, 

 issued principally in Germany, without which the search for the dis- 

 coveries of a little-known author would be well-nigh hopeless. Much 

 useful work has been done in this direction in connection with our 

 Association. Such critical reports as those upon Hydro-dynamics, upon 

 Tides, and upon Spectroscopy, guide the investigator to the points most 

 requiring attention, and in discussing past achievements contribute in 

 no small degree to future progress. But though good work has been 

 done, much yet remains to do. 



If, as is sometimes supposed, scienc i.sisted in nothing but the 



laborious accumulation of facts, it would soon come to a stand-still, 

 crushed, as it were, under its own weight. The suggestion of a new 

 idea, or the detection of a law, supersedes much that had previously been 

 a burden upon the memory, and by introducing order and coherence 

 facilitates the retention of the remainder in an available form. Those 

 Avho are acquainted with the writings of the older electricians will under- 

 stand my meaning when I instance the discovery of Ohm's law as a step 

 by which the science was rendered easier to understand and to remember. 

 Two processes are thus at work side by side, the reception of new 

 material and the digestion and assimilation of the old ; and as both are 

 essential, we may spare ourselves the discussion of their relative impor- 

 tance. One remark, however, should be made. The work which deserves, 

 but I am afraid does not alwaj-s receive, the most credit is that in which 

 discovery and explanation go hand in hand, in which not only are new 

 facts presented, but their relation to old ones is pointed out. 



In making oneself acquainted with what hag been done in any subject, 



