August 1, 1884.] 



SCIENCE. 



97 



growing scholars around them, the next be- 

 ing a consciousness that they are responsible 

 for what thej' do to the world of science and 

 letters, and not merely to their own colleagues 

 and followers : and, finally, they must not only 

 be fairly paid, but must be protected from 

 temptations to every form of extravagance in 

 the employment of their resources. Such are 

 some of the difficulties which are to be encoun- 

 tered when the simple idea of ' first-rate teach- 

 ing' is expanded. 



All that Mr. Bryce says about the end of an 

 education is excellent: "It is not to train 

 students merely as lawyers, physicians, cler- 

 g3'men, engineers, bankers, merchants, and 

 statesmen, but as men ; and the best thing 

 the university can do for them is to form in 

 them what w T e will call the philosophic mind." 



TH UNDER-S TORMS, 



Benjamin Franklin once remarked, in sub- 

 stance, sadly to a friend, "It is now eight 

 years since I showed that mankind could be 

 protected from the danger of lightning by 

 lightning-rods ; yet there is hardly a house in 

 Philadelphia provided with them." The heart 

 of the great American philosopher would be 

 greatly warmed if he could perceive the activity 

 of his disciples, who wayla}- every builder of a 

 house, and awaken fears where all was peace 

 before. There is no question oftener asked of 

 the professor of physics than this : " Shall I put 

 lightning-rods on nry house, and, if I erect 

 them, what should be their form and position ? " 

 Personally I have given the following abbre- 

 viated answers. "If your house is surrounded 

 by tall trees, or if there are higher houses in 

 your immediate neighborhood, I should trust 

 to the trees, or kindly leave the expense of the 

 lightning-rods to your neighbor. If your house 

 stands alone, a prominent point in the land- 

 scape, on a cliff, or remote from trees, I should 

 be in favor of a properly placed lightning-rod. 

 I should place two or three pointed rods three 

 or four feet above the highest point of the 

 house ; allow the metallic rod, which should be 

 at least one-halfa square inch in section, to rest, 

 without glass insulators, upon the house ; con- 

 nect all the tin sheathing, the copper gutters, 

 the gas and water pipes, with this lightning-rod ; 

 and conduct the latter, by the shortest course 

 possible, to wet earth." 



These answers seldom conclude the corre- 

 spondence, however, although one generally 

 prefers to leave to the neighbor the expense of 

 erecting lightning-rods. One brings instances 

 of houses having been struck which are situated 

 lower than one's neighbors, and are surrounded 

 with tall trees which over-topped the houses ; 

 and one asks with a shudder, " Can I connect 

 my gas-pipes with a lightning-rod? " Indeed, 

 the w r riter or would-be authority on lightning- 

 rods has not an easy life before him. He must 

 not onl} T satisfy the timid heart of the believer 

 in him, but he must also fight with all his knowl- 

 edge the brazen limb of ignorance and super- 

 stition, who starts with the postulate that no 

 scientific man knows any thing concerning thun- 

 der and lightning, and that the true knowledge 

 has been revealed only to himself while working 

 in a cornfield. It is not long since, that an 

 American professor of physics was sued for 

 twenty or thirty thousand dollars damages for 

 maintaining that the members of a lightning- 

 rod company which placed lightning-rods like 

 a letter U upon the roofs of houses were prac- 

 tically quacks ; the theory of this lightning-rod 

 being, that the lightning, if it struck one point 

 of the U, would be dissipated into the air from 

 the other point. There is a lightning-rod 

 company in Massachusetts at the present time 

 which erects lightning-rods on the theory that 

 lightning always seeks electrical earth-cur- 

 rents ; and, if there are earth- currents beneath 

 a house, that house should be protected, and 

 the rods led into the path of the earth-current. 

 If, on the other hand, no earth-currents run 

 near the house, such a house is safe, and needs 

 no lightning-rods. The electrician of this firm 

 is self-taught : there are no books on electricity 

 in his library. He discovers the earth-currents 

 by a forked stick. Not deterred by the fact 

 that there is no evidence to prove that a dis- 

 charge takes place between a charged cloud 

 and a current of electricity in the ground, and. 

 moreover, no evidence to prove that earth- 

 currents move in regular paths through the 

 earth, and, indeed, no conclusive evidence of 

 the existence of earth-currents, he persuades 

 even the so-called practical electrician to re- 

 arrange the lightning-rods on his house. 



The student of electricity is therefore called 

 upon to assert the grounds of his belief : and he 

 finds it difficult to convince his audience ; for 

 they are, in general, not sufficiently conversant 

 with electrical phenomena to appreciate his 

 arguments. The position taken by most pro- 

 fessors of physics on the subject of lightning- 

 rods is based upon the experiments of Franklin, 

 in which he showed that pointed metallic rods, 



