4i6 



NA TURE 



[March 4, 1880 



" 10. In melting metals. 



" 1 1. In firing inflammable substances. 



"12. The sulphurous smell. The electric fluid is at- 

 tracted by points, and we do not know whether this 

 property is in lightning. But since they agree in all the 

 is wherein we can already compare them, is it 

 not probable that they agree likewise in this? Let the 

 experiment be made." 



The early experiments with lightning-rods, and their 

 gradual spread in Europe, are detailed in the succeeding 

 chapters, with a variety of information of various kinds 

 extremely interesting to the general reader, and dealing 

 with such topics as the priestly opposition to the "hereti- 

 cal rods," the childish jealousy of the Abbe" Nollet, and 

 the dispute whether the rods should be furnished with 

 points orballs at their summit. SirW. Snow Harris's labours 

 are treated of in a chapter by themselves, and another is 

 devoted to full descriptions of the systems of lightning- 

 protectors adopted in the Hotel de Ville, Brussels, and in 

 the Houses of Parliament — both complete in their way. 

 A ch ipter on weather-cocks and the methods devised for 

 making them do duty also as lightning-conductors, gives 

 practical information on points which we do not recollect 

 having met with elsewhere. The concluding sections 

 deal with Newall's system of protecting buildings, with 

 accidents froai lightning — a black catalogue — and the 

 book ends with two suggestively practical chapters on the 

 earth connection and on inspection of lightning-conduc- 

 tors. Apart from mere literary merits, these two chapters 

 constitute the strong point of the work. At great pains 

 Mr. Anderson points out how a good earth connection is 

 the alpha and omega of protection from lightning. He 

 shows how the pretentious paratonnerres which adorn 

 with their immense proportions so many thousands of 

 buildings in France, often fail for want of thorough 

 continuity to " earth ; " and, after citing case upon case, 

 declares as the result of his experience that "'probably in 

 nine cases out of ten, whenever a building provided with 

 a conductor is struck by lightning, it is for want of 'good 

 earth.'" He quotes Franklin's advice drawn up for the 

 Royal Society in 1772, on the occasion of the Government 

 pn viding protection for the great powder-magazines at 

 Purfleet, that " at each end of each magazine a well 

 si •aid be dug, in or through the chalk, so deep as to 

 have in it at least four feet of standing water," in which 

 to terminate the conductors. Mr. Anderson prominently 

 advises the utilisation of the systems of gas and water- 

 pipes to this end in all buildings which stand upon a dry 

 soil. 



Very strongly, but not too strongly, docs the author 

 dwell on the importance of connecting to the main con- 

 ductor all large masses of metal about a house, all lead 

 roofs and gutters, all metallic ridge-tiles and roof-orna- 

 ments, and all water-spouts. In the absence of these he 

 would even carry conductors over all the prominent edges 

 of bail lings. The foolish system of insulating the 

 lightning-conductor from the building by glass or porce- 

 lain holders, he unsparingly condemns. With his remarks 

 on the importance of periodic inspection of lightning- 

 conductors to test by galvanometer and battery the actual 

 efficiency of the rod, and, above all, its earth connection, 

 we cordially agree. There can be no doubt that a bad 

 conductor is far worse than no conductor at all ; and that 

 the inmates of many " protected " houses dwell — so far as 



their fancied security from lightning is cjneerned — in a 

 fool's paradise. 



The author describes a simple and portable form of 

 apparatus specially adapted for testing the efficiency of 

 lightning-conductors. It consists of three cells of a 

 modified Leclanche" battery of small internal resistance, a 

 tangent galvanometer, and five keys for throwing at 

 pleasure three different resistances into the circuit and 

 comparing them with the resistance of the conductor. 



While making no show of a knowledge of electrical 

 theory, the author's language and arguments seldom clash 

 with modern ideas as to the nature and laws of elec- 

 tricity. Nevertheless, in a work of this kind wc should 

 have been glad to find a little more direct reference to 

 the scientific and theoretical aspects of the subject. Wc 

 hardly think that the explanation given on p. 70 of the 

 "return stroke" would be found adequate by one who 

 met with the subject for the first time in these pages. 

 The definitions of units given on p. 59 are unfortunately 

 incorrect. The connection between the normal and ab- 

 normal eiectric conditions of the air is barely touched ; 

 indeed, the only reference to the subject of "atmospheric 

 electricity" we have found in the text is to the rather 

 antiquated views of Peltier. The researches of Sir W. 

 Thomson, Dr. Everett, and others on this subject are 

 not even alluded to. We regret that the author speaks 

 somewhat disparagingly of the valuable little "note" on 

 the protection of buildings, published a few years ago by 

 Prof. Clerk Maxwell, and we think the author has not 

 quite apprehended it, in the matter of the earth con- 

 nection, in the sense intended by its Lite lamented 

 writer. 



The work contains also a list of books relating to the 

 lightning-conductor, a list of all the important observations 

 of accidents by lightning, and an excellent and singularly 

 complete bibliography of the whole subject. The illus- 

 trations are numerous and good, and are free from the 

 objectionable sensational character which writers on this 

 and kindred topics sometimes tolerate. S. P. T. 



OUR BOOK SHELF 



Medicinal Plants; being Descriptions, ■uitli Origin?./ 

 Figures, of the Principal Plants employed in Medicine, 

 and an Account of their Properties and Uses. By 

 Robert Bentley and Henry Trimen. 4 vols. (London : 

 J. and A. Churchill, 18S0.) 

 IT is not often that a reviewer can rise from a critical 

 examination of a Hire de luxe with such an unmixed 

 feeling of satisfaction as in the case of these hand- 

 some volumes. At the close of their four years' labours 

 the authors have succeeded in maintaining the high 

 standard which they set before them at the outset. We 

 do not mean that the level is absolutely uniform through- 

 out. Admirable as the coloured plates — nearly all of them 

 new — are on the whole, there are some few which fail in 

 giving a perfectly satisfactory representation of the plant 

 depicted. The letter-press descriptions also vary, in 

 quantity if not in quality, for which the authors account 

 " from the varying interest taken in substances at different 

 times, some new remedies exciting much attention, and 

 thus demanding a full description, though not, perhaps, 

 of great permanent value." But when we recollect that 

 the number of species described and depicted is 306, 

 including every medicinal plant recognised by the official 

 pharmacopoeias of Britain, India, and the United States, 

 with a few others in addition, small inequalities of this 



