292 



NA TURE 



[January 30, 1902 



M. Eiffel refers at length, has possibly revived since the 

 falling off of receipts on the occasion of the last exhibi- 

 tion, and the well-earned reputation of the author may 

 have suffered in consequence. Certainly no less than 

 three descriptions of the Tower have emanated from the 

 eminent engineer in a short space of time. The first, 

 entitled " La Tour de trois cents Metres," was an oui'rai^c 

 tie luxe, a massive folio volume with sixty-seven plates, 

 also in folio. This work, mtended for experts, has been 

 presented to various public libraries and scientific 

 societies, and will be consulted with interest by those 

 engaged in similar projects of construction. Next ap- 

 peared, in a more handy form, " Travaux Scientifiques 

 executes a la Tour de trois cents Metres," which, though 

 not generally circulated, was intended to form a complete 

 refutation to those who still urged the plea of inutility 

 against the structure. The present volume appears to 

 follow a middle course between these two, the author 

 giving an account of the history of the construction of the 

 Tower, the modifications that were suggested, after the 

 experience gained in 1889, to make it more accessible 

 to visitors in 1900, together with some account of the 

 scientific investigations which this unique structure 

 rendered possible or facilitated by reason of its height 

 and form. 



We have here, therefore, a complete history of the 

 building from the date of its proposal in 1886 up to the 

 present time, and of necessity many of the details have 

 already appeared in the public journals, while the authors 

 of the scientific work that has been carried on in con- 

 nection with it, having contributed their results to various 

 scientific bodies, have had them published in due course, 

 and these have been commented on in our columns from 

 time to time. As an example, one may refer to M. 

 Janssen's researches on the telluric origin of the lines of 

 oxygen in the solar spectrum, which were carried out in 

 1889. The \akieofthe book consists in the complete- 

 ness of the historical details and the ready access it 

 offers to much that has been accomplished in connection 

 with the Tower, particularly in the way of meteorological 

 observations. M. Eiffel naturally thinks it a complete 

 answer to his detractors, but whether this be so or not, 

 it is impossible not to recognise that the management 

 has welcomed with loyalty and assistance every scientific 

 project that has been recommended to its consideration. 

 One gathers that in the view of the promoters, the Tower 

 was never intended to be either a scientific laboratory or 

 a judicious pecuniary investment. We may quote here 

 M. Eiffel himself: — 



" 11 me semble que, n'eut elle pas d'autre raison d'etre 

 que de montrer que nous ne sommes pas simplement le 

 pays des amuseurs, mais aussi celui des ingenieurs et des 

 constructeurs c[u'on appelle de toutes les rdgions du 

 monde pour cdifier les ponts, les viaducs, les gares et les 

 grands monuments de I'industrie moderne, la Tour Eiffel 

 mdriterait d'etre traitee avec consideration.'' 



And again : — 



" Etant la plus saisissante manifestation de I'art des 

 constructions metalliques par lesquelles nos ingenieurs 

 se sont illustres en Europe, elle est une des formes les 

 plus frappantes de notre genie national moderne." 



Looked at from this point of view, its existence is its 

 iustification. It accomplished what was demandedof i t, 

 NO. 1683. VOL. 65] 



and its scientific applications, useful as some of them 

 may be, are no more than an ornamental fringe to the 

 main design. 



In 1889 nearly two million visitors paid for admission 

 or ascent, and the lifting apparatus had been taxed to 

 the extent of carrying 23,000 persons in a day. With the 

 view of offering greater accommodation on the occasion 

 of the exhibition in 1900, when as great or greater 

 numbers of visitors might be expected, it was determined 

 to increase the accommodation on the various platforms 

 and to rearrange the mechanism of the lifts so that a greater 

 number of ascents could be made per hour. The altera- 

 tions, necessarily of a costly character, are described in 

 very great detail, and when completed provided for the 

 partial or complete ascent of 3120 passengers per hour, 

 instead of 26S0 per hour, as in 1889. Or regarded from 

 another point of view, while the total receipts under the 

 old system could not exceed 5240 francs per hour, under 

 the new arrangement, with a lower tariff, the hourly 

 receipts could amount to 7120 francs per hour. A great 

 deal of work had to be effected, and the manner of its 

 accomplishment, interesting to experts, will be found set 

 out with great clearness and precision. How the san- 

 guine expectations were disappointed is a matter of 

 history, and the falling off in the number of visitors to 

 about one-half is to be regretted; but the efficiency of the 

 arrangements and the success with which they worked 

 should be a matter of congratulation from an engineering 

 point of view. 



Having disposed of these mechanical arrangements, 

 to which are added some interesting statistics connected 

 with the financial side of the question, M. Eiffel gives 

 some account of the various scientific purposes to which 

 the Tower has been put during the last eleven years. 

 These, referring to meteorology, to atmospheric electricity, 

 to the construction of a manometer for high pressures, 

 and a variety of other researches, have been mentioned 

 in these columns at the time the different physicists en- 

 gaged in the work published the results of their investi- 

 gation. Although mention has already been made of 

 wind observations in connection with the Tower, notably 

 in vol. xlix. p. 596, and li. p. 181, we are tempted to 

 return to this question and give the results of a simple 

 investigation conducted by M. Eiffel to detect the amount 

 of motion that the structure experienced under the in- 

 fluence of a high wind. It will be remembered that the 

 opponents to the scheme of construction in the early days 

 made a strong point of the difficulties that would ensue 

 from excessive wind pressure, and the point is interesting, 

 not only on that account, but because a great deal of loose 

 information is current concerning the motion of tall chim- 

 neys and steeples. Anemometry, when applied toconsider- 

 able areas, is not in a very satisfactory condition, and the 

 necessary strength to be given to buildings is more or 

 less a matter of conjecture and experience. M. Eiffel's 

 method of observation was exceedingly simple. On the 

 third platform, at a height of 309 m., was placed a 

 diagram of concentric circles alternately coloured white 

 and red, each 20 mm. in breadth, and ten in number. 

 The centre of this target, if it may be so described, was 

 made to coincide with the intersection of the cross wires 

 of a solidly mounted theodolite at the base of the eastern 

 pillar. It seems to have been assumed that the telescope 



