Nov. 27, 1884] 



NA TURE 



81 



attraction — and in one other fact, which is this. It is absolutely 

 impossible to prove that any stroke at all would have occurred 

 it the h..use if the attractive conductor had not been present. 

 Granted, we (opponents) say, that your conductor, if in good 

 order, may be the means of averting the terrific force of the 

 explosion from the non-conducting materials of the building 

 when once the stroke has been developed, we nevertheless prefer 

 that our houses should receive no stroke at all. We infinitely 

 prefer to run the extremely unlikely chance of ever being visited 

 by a lightning-stroke to the practice of deliberately inviting such 

 a stroke to our houses, and of trusting to the excellence of the 

 rod-manufacturer's arrangements to avert any portion of its 

 effects from the inmates and the structure. 



Holding, then, as we do, that the principle of the lightning- 

 rod, t/ud its necessary exposure of additional elevated metal on 

 a building, is vicious, and that nothing of a beneficial nature due 

 to the preventive power of its point (if it have one) can obliterate 

 this dangerous tendency, the undoubted disadvantages of the 

 system, due to the defects in practice that habitually accompany 

 the employment of rods, appear to be minor points, but the 

 reviewer's reasoning on this branch of the subject is worthy of 

 remark. He says (p. 52) : "The failures incident upon de- 

 fective work — as all unbiased and properly-trained thinkers are 

 aware — are amongst the weightiest of the arguments that tell in 

 favour of the employment of conductors." This sentence is 

 wholly beyond my own reasoning power. Because (ceteris 

 paribus) an apparatus is liable to failure on account of being 

 defectively constructed, /// refore it should be employed ! He 

 goes on to say : — " In a very large majority of the cases in which 

 accidents have occurred to buildings which have been furnished 

 with lightning-conductors the mischief has actually been traced 

 by competent inquiry to some easily recognised fault or deficiency 

 of construction." Allowing that even in all cases in which these 

 disasters had occurred this statement were true, what does it 

 show? Why, simply the very cheap sort of perception known 

 as wisdom after the event. The manner in which, after the blow 

 has happened, ingenious excuses are constantly made for the 

 unfortunate conductors, which previous to the event had never 

 been found fault with, is to the opponents of rods one of the 

 most amusing and least edifying circumstances that environ the 

 use of these instruments. But I would now venture to submit a 

 few statistics derived from researches specially made by me 

 during the last five years in regard to strokes and accidents in 

 connection with lightning-rods. Up to date I have collected the 

 fullest details of 320 well-authenticated ca-es. In 204 of these, 

 or 64 per cent., injuries either to rods, constructions, or 

 persons, occurred. In 151 cases, 01-47 per cent., there were 

 injuries either to constructions or to persons. Out of these 

 151 incidents, 71 contain in their records no allegations as 

 to the existence of faults, either in the rod or in its "earth," 

 until after the event, and the remaining 80 furnish no record 

 of such faults being found either before or after the event. And 

 indeed the whole of the results of my researches afford evidence 

 (and especially in regard to the "earths" of rods) that failures 

 and accidents more frequently happen with rods in what is 

 deemed good order, than with those considered after the event 

 e been in bad order. 

 The reviewer in his enthusiastic advocacy of lightning-rods 

 advises his followers not to be content with single, or even a 

 Is on their houses, but to cover them with "a broadly- 

 cast net of metallic meshes and lines." And he concludes with 

 the following sentence: — "The free and frequent use of the 

 testing galvanometer is the natural consummation of the bene- 

 ficent work which was initiated by Franklin 130 years ago. 

 Without this instrument the lightning-conductor is a hopeful and 

 v :v generally helpful expedient. But with the galvanometer it 

 is ni iw assuredly competent to take rank as a never-failing pro- 

 tection." These dicta aptly conform with the reviewer's tactics 

 in respect of the practical question of the cost of lightning- 

 conductors. Here again, as in the case of the preventive power 

 of i" lints, he never mentions the subject. He seems to think 

 that persons of common sense are capable of throwing "a 

 broadly-cast net of metallic meshes and lines " of the purest 

 coppei over their houses, and of entertaining at frequent inter- 

 vals the services of electrical testers to attend to these meshes 

 and lines, without first counting the cost. He is perhaps 

 unaware that (according to Sir William Thomson) the Glasgow 

 manufacturers think it cheaper to insure their factorii ra ''•>■• 

 than to employ lightning-rods. But surely in regard to the 

 statement that the use of the galvanometer makes the lightning- 



conductor a " never-failing protection," there is some little 

 obscurity in the premises and conclusions. It is well known 

 that rod advocates recommend the use of the galvanometer 

 principally in order to test the resistance of the rod's " earth." If 

 this resistance should prove to be above a certain standard, they 

 say that the rod is not only useless, but dangerous. How is 

 the mere fact of the knowledge that a rod is useless, or that its 

 earth-resistance is too great, a " never-failing protection" ? And 

 what remedial measures can possibly obviate the dryness of the 

 ground? One might as well say that the services of a physician 

 who, having tested his patient's state of health, should tell him 

 that he was in a bad way, and should then dismiss him, consti- 

 tuted a " never-failing protection." In the case of the rod the 

 only protective feature appears to me to lie in the probability 

 that most persons who were also " unbiased and properly- 

 trained thinkers," on being informed that the galvanometer had 

 demonstrated their rods to have a too great "earth" resistance, 

 would immediately pull them down. But obviously this is 

 hardly the reviewer's meaning. ARTHUR PARNELL 



S3, Fulham Park Gardens, November 17 



Government Scientific Books 



Shortly after the commencement of the publication of the 

 " Scientific Results of the Voyage of H.M.S. Challenger" by 

 the Government, the late Mr. T. C. Cobbold, M.P. for Ipswich, 

 inquired in the House of Commons whether, inasmuch as this 

 expedition was undertaken with the nation's money for national 

 scientific purposes, a copy of the volumes as published would 

 not be presented to the public libraries supported by public 

 rates, &c. The Government reply was that the expense of sup- 

 plying the work gratis to such libraries in the different towns 

 throughout the country would be too large. 



I sh Duld like to ask whether it would have cost anything like 

 the 87,500/. which the Government has recently paid for only 

 two pictures from the Blenheim collection, and whether the 

 ratepayers throughout the country have not a far greater right 

 to be supplied (through their libraries) with the opportunity of 

 seeing and studying the results of their own scientific expeditions 

 than the remote opportunity of seeing these two 87,500/. paint- 

 ings at Kensington. 



I see by your advertisement that the tenth volume, at 50*-> °f 

 the " Challenger Reports" is just published. What chancehave 

 thousands like myself of ever seeing them. Our public museum 

 library cannot afford to purchase them, though I have little 

 doubt but that our town, with its 50,000 inhabitants, has more 

 than paid for a copy of the Reports in its share towards the 

 expense of the Expedition and the publications resulting there- 

 from. 



As a country ratepayer I must protest against this centralisa- 

 tion of all the great works in art and the benefits and results of 

 scientific expeditions in London. Some of your correspondents 

 have complained that such national publications are not supplied 

 to great national libraries abroad, but how is it that even we who 

 have had to pay for them cannot ever get a sight of the results 

 of such interesting and important national scientific expeditions. 

 " Cannot afford it" is the Government reply, but how then can 

 they afford 87,500/. for two paintings for the national galleries? 

 I do not grudge the expenditure of the people's money for the 

 latter, only when set off against the "cannot afford "for the 

 former. W. Budden 



Ipswich, November iS 



P.S. — I have the two volumes of Sir C. W. Thomson's 

 " Voyage of the Challenger" but they have only tended to create 

 a greater desire to see the complete "Government Reports," a 

 wish, ala^, which, from the expenditure of the 87,500/. for pic- 

 ture- by the Government, is further off than ever. 



Peculiar Ice Forms 



Abslnxe from town prevented me from seeing Nature of 

 November 6, in which there is a letter (p. 5) signed B. Woodd 

 Smith with the above heading. 



Possibly Mr. Smith's very ingenious explanation of the cause 

 of the columnar form of the shallow stratum of ice he so well 

 describes may be the correct one ; yet perhaps I may be per- 

 mitted to offer a very different solution of the difficulty connected 

 with this very curious ice formation. 



I have frequently noticed, both on lakes having deep water 



