April 7, 1898] 



NATURE 



537 



a sliding clamp so as to be raised and lowered. The bending of 

 the brass strip under the attraction of the magnet on the ball 

 was measured by means of a telescope and scale, the mirror 

 being fastened to the end of the strip. As the motion of the 

 ball was entirely in a plane perpendicular to the axis of the 

 magnet, the law of variation of force must have been very nearly 

 the same as in the orbit experiments. 



When the ball was directly over the true pole, which lay about 

 I cm. from the end of the conical pole-piece, the law was nearly 

 that of the inverse cube, the observations being taken between 

 the limits of 3 cm. and 14 cm. from the axis of the magnet. 

 Other series were taken with the plane of motion of the ball at 

 different distances from the pole, and it was found that with the 

 plane of motion at 2 '8 cm. from the true pole the law of the 

 inverse square was very closely obeyed between 4 cm. and 14 cm. 

 from the axis. These limits cover the region in which the orbits 

 would in most cases be formed. The exact law of force as 

 determined by least squares from seven observations between 

 the above limits was that of the 2"i power of the distance. 



Louis W. Austin. 



The University of Wisconsin, Madison, Wis., March 16, 



An Extraordinary Heron's Nest. 



I SEND you a photograph of probably the most extraordinary 

 heron's nest ever discovered in this or any other country. During 

 a gale it was blown from the top of an elm tree in the heronry 

 on Stoke Hall estate in Notts, the seat of Sir Henry Bromley, 

 Bart. It is of unusual size, and almost exclusively composed of 

 wire of varying lengths and thickness; the centre, or "cup," 

 alone being composed of fine twigs, grasses and feathers. 

 Several other nests of the heronry, which had also been blown 

 down, contained pieces of wire cleverly worked in with twigs in 

 the usual way, but this was the only one entirely composed of 

 that material, as far as the main structure is concerned. There 

 are happily now a very flourishing heronry at Dallam Tower, 

 Westmorland, the seat of Sir Henry Bromley's son, Mr. Maurice 



Bromley- Wilson, and although I have been familiar with it " off 

 and on " for very many years, and with several other heronries 

 in various parts of the country, I never knew of the birds using 

 wire in the construction of their nests. I have several records 

 of rooks using wire in large quantities in the construction of 

 their nests. Particulars of one very remarkable instance were 

 published in the Yorkshire Weekly ^i?j/of May 19, 1894, and of 

 another in the same paper for June 23, 1894. Both of these 

 freaks took place in India : one at Calcutta, the other at Ran- 

 goon. The other curious feature of the Stoke Hall phenomenon 

 is that there is, and never has been, any lack of ordinary building 

 material, and that all the wire used must have been carried a 

 great distance. G. W. Murdoch. 



Westmorland. 



" The Story of Gloucester.' 



Referring to your article (p. 221), I think you cannot have 

 looked at pages 70 to 117 of the Gloucester Small-pox Epidemic 

 Blue Book, by Dr. Coupland. I have analysed all these cases, 

 and here is the result. 



Description. 



" Unvaccinated " — 



These contain 21 cases, 10 

 deaths, whose description in- 

 cludes the word vaccination 



or vaccinated 



"Vaccinated in infancy," no de- 

 scription of vacc. marks 

 Do. "no marks," very abundant 



small-pox eruption 



Do. "one" vacc. mark 



Do. two do 



Do. three do 



Do 4, J, 6, 7 and 8 vacc. 



marks 



Do. (?) v. marks, very abundant 

 eruption 



Cases. 



Totals 



679 



788 



35 



30 



100 



141 



197 



1979 



Deaths. 



287 

 91 



13 



3 



10 



13 

 13 



4 



Deaths 

 per cent, 

 of cases. 



434 



42 'Z 



"•5 



37'i 



10 o 



10 'O 



92. 



6-5 

 44'4 



21*9 



The accepted fatality before Jenner's birth was ... 166 



There were — Cases. Deaths. 



v^£- vaccinated cases at Gloucester 173 9 S'2 



These had all kinds of v. marks up to 8 in number, and some 

 had been repeatedly xt-v2iCcmditGA ; one "often" re-vaccinated. 

 If the same energy had been put into a critical proof of the 

 vaccination of each one as was into avoiding condemning 

 vaccination, there would be little to show, even in fatality, in the 

 above /^r vaccination ; as it is, it kills every vaccine dogma. 



Alex. Wheeler. 



NO. 1484, VOL. 57] 



Mr. Wheeler, it must be assumed, is wishful to prove that 

 the fatality amongst the vaccinated is as high, or at any rate is-* 

 not lower than amongst the non-vaccinated. It is surely not 

 necessary for him to separate vaccinated cases into those " with 

 marks" and those with " no marks," since to him it should be 

 immaterial whether a patient be vaccinated or not. 



Taking Mr. Wheeler's own classification, we find that of the 

 unvaccinated cases, 679 in number, 287 died, giving a per- 

 centage mortality of 42-2 ; whilst of the vaccinated cases, 1300 

 in number, only 147, or 11-3 per cent., died. These figures, 

 should surely be enough to settle the question as regards per- 

 centage mortality, and the mere inclusion of the 21 cases and 

 10 deaths, whose description includes the word "vaccination" 

 or " vaccinated," does not in any way invalidate the general 

 conclusions to be drawn from these figures. 



If now, however, a class for the " under- vaccinated " be 

 included, the second class may be divided into "under-vaccin- 

 ated" 89 cases with 27 deaths, or 30-3 per cent.j and vaccin- 

 ated 12 II with 120 deaths, giving a mortality of only 9*9 per 

 cent. It is evident that Mr. Wheeler's table in no way conflicts 

 with the figures given in the Report (except in one small parti- 

 cular, noted below), but is based on a misconception of the term 

 " under- vaccination " as used by Dr. Coupland, who used the 

 term to signify those cases of small-pox which had undergone 

 vaccination at any time within the (generally accepted) period 

 of incubation : i.e. fourteen days before the appearance of the 

 rash. In the list of " unvaccinated " cases are included a few 

 which were actually vaccinated in the invasion period. No 

 doubt some of these should be placed in the vaccinated class ; 

 but others, again, should be grouped in the unvaccinated class. 

 The Royal Commission reckoned the whole group, instead 

 of a large proportion, in this latter class, which is perhaps not 

 strictly scientific and accurate. Mr. Wheeler, however, goes 

 far further astray in including them all in the vaccinated class, 

 which is clearly erroneous. It may be pointed out in this con- 

 nection that, in his recently published work. Dr. Cory gives 

 some most interesting facts which tend to show that vaccinal 

 immunity is not obtained until nine days have elapsed after 

 inoculation. It would be easy, therefore, from the table on 

 page 149 of the Report, to divide the total 89, there reckoned 

 as "under vaccination," into two sections : {a) those vaccinated 

 before, and (b) those vaccinated within eight days, of manifesting 

 small-pox. If this were done, there would be added (a) to the 



