LESSONS IN ELECTRICITY. 



885 



by \vhich natural phenomena are regulated. 

 A V I r.\ iy I) !(T'i!i'>(l \>\ r ;i thunder-storm ; 

 bi.-iU r.viv .<: i l > IO.J-M, ;irrl e t \->. return to 

 llioi stall-* <ii!rin<: a* -1-r ei lir^- ; bill neither 

 birds n >r can!", in f;ir r-t wo know, ever 

 think of inquiiing int > tie causes of th^c 

 things. It is ntnerwise with man. Tho 

 presence of natti-al object?, the. occurrence 

 of mtii'-al event- 1 , l!n?va*ied apnearances of 

 lh". universe in which he dwi 1's, pent Irate 

 beyond his organs of sense, and appeal to an 

 inner power of which the scnsts aie the mere 

 instrum r nts an'l excitants. No fact, is to 

 him either final or original. II u cannot limit 

 hinnelf i) the contemplation of it alone, but 

 endeavors t-> ascertain its position in a series 

 to which the con.-.tit;ili M n of his mini assures 

 him il must bcl ing. H* icgarels all that he 

 witnesses in the present as the efflux and 

 sequence of s m^thina; that has gone before, 

 an I a< the source of a system of events 

 whifh is to follow. The notion of spon- 

 tam'ily, v which ia his ruder state ho ao- 

 countcd for natural events, is abandoned ; 

 the i'lfu that Nature is an aggregate of inde- 

 pendent pruts also disappears, as the connec- 

 tion an 1 mr.tunl dependence of physical pow- 

 ers b'v.mo mo'e and rmre manifest ; until 

 h'i i.-> finally led. and that chiefly by the sci- 



1 cncf! of which 1 happen this evening to be 

 the exponent, to regaul Nature as an organic 

 whole, as u body each of whose members 

 sympathizes with the rest, changing, it is 

 true, from ages to ages, but without one real 

 bieak ' f continuity, or a single interruption 

 of the fixed relations of cause and effect. 



The system of things which we call Nature 

 is, however, too vast and various to be studied 

 first-han I by any single mind. As knowledge 

 exten Is there is always a tendency to sub- 

 divide the fiel.l of investigation, its various 

 paits being taken up by different individuals, 

 and thus receiving a greater amount of atten- 

 tion than could possibly be bestowed on them 

 if each investigator aimed at the mastery of 

 the whole. East, west, north, and south, the 

 huaian mind pushes its conquests ; but the 

 centripetal form in which knowledge, as a 

 whole, advances, spreading evor wider on all 

 sides, is due in reality to the exertions of in- 

 dividuals, each of whom directs his efforts, 

 more or less, along a single line. Accepting, 

 in many respects, his culture from his fellow- 



. xmro, taking it from spoken words and from 

 written books, in some one direction, the stu- 

 dent of nature mut actually touch his work, 

 lie may otherwise be a distributor of knowl- 

 edge, but not a creator, and fails to attain 

 that vital it v r-f tli ought and correctness of 



judgment w 7 hich direct and habitual contact 

 with nitiirfil truth can alone impart. 



One large department of the system of Na- 

 ture which forms the chief subject of my own 

 I'.tudie.s, and to which it is n:/ duty to call 

 your attention this evening. '... thai (.f PU\MC.-. 

 or natural philosophy. This term is "large 



! uiougtito cover tiie study of Nature gen- 

 erally, but it is usually lestricted to a dcpert 

 mem which, perhaps, l.es closer to our per-, 

 tnaa any oilier. It deals with the 



phenomena and laws of light and heat with 

 the phenomena and laws of magnetism and 

 electricity with those of sound with the 

 pressures and motions of liquids and gases, 

 whether in a state of translation or of undula- 

 tion. The science of mechanics is a portion 

 of natural philosophy, though at present so 

 large as to ne,ed the exclusive attention of him 

 who would cultivate it profoundly. Astron- 

 omy is the application of physics to the mo- 

 tions of the heavenly bodies, the vastness of 

 the field causing if, however, to be regarded 

 as a department in itself. In chemistry 

 physical agents play important pa*ts. By 

 heat and light we cause bodies to combine, 

 and by heat and light we decompose them. 

 Electricity tears asunder the locked atoms of 

 compounds, through their p^wer of separat- 

 ing carbonic acid into its constituents ; tine 

 solar beams build up the whole vegetable 

 world, and by it the animal, v/hile the" touch 

 of the self-same beams causcn hydrogen and 

 chlorine to unite with sudden explosion and 

 form by their combinal ion a powerful acid. 

 Thus physics and chemistry inter mingle, 

 physical agents being empk.yid by the chem- 

 ist as a means to an ind ; while in physics 

 proper the laws and phenomena of the agents 

 themselves, both qualitative and quantitative, 

 are the primary objects of htlention. 



JVly duty heie to-night is !o t-pind an hour 

 in telling how this* subject is t > bj studied, 

 and how a knowledge of it is lj bo imparted 

 toothers. W hen first invited to do ihis, I 

 hesitated before accepting the icsponsibil.iy. 

 It would be easy to tnteitaiu you with an ac- 

 count of what natural philosophy hap accom- 

 plished. I might point lo those application* 

 of science regarding which we hear so much 

 in the newspapers, "and which we often find 

 mistaken for science itself. I might, of 

 course, ling changes on the .steam-engine and 

 the telegraph, the electrotype and the photo- 

 graph, the medical applications of physics, 

 and the million other inlets by which tcieo- 

 tific thought filters into practical life. That 

 would be easy computed with the task of in- 

 forming you how ycu arc to make the study 

 of physics t he instrument of your own culture, 

 how you are to possess its factu and make 

 them living seeds which shall take io:.t and 

 grow in the mind, and not lie like de:ul lum- 

 ber in the storehouse of memory. This is a 

 task much heavier than the mere cataloguing 

 of scientific achievements ; and it is one 

 which, feeling my own w:ini cf time and 

 power to execute it aright, 1 might well hesi- 

 tate to accept. 



But let me sink excuses, and attack the 

 work to the best of my ability. First and 

 foremost, then, I would advise you to get a 

 knowledge of facts from actual oboei vuii^n. 

 Facts looked at directly are vital ; when they 

 pass into words half the sap is taken out cf 

 them. Ycu wish, for example, to get a 

 knowledge of magnetism ; wul, provide your- 

 S( If with a good bock on the subject, if ycu 

 can, but d) not be content with what the 

 book tells you ; do not be satisfied with its 

 descriptive wood-cuts ; see the actval thing 



