ii6' 



NA TURE 



June 2, 1892 



in some places, and slicking to the clay cylinder. This, I think, 

 is suffieient evidence that the clay, or sojie impurity contained 

 in it, attacks the wire, otherwise the local nature of the action 

 could not be explained, unless the quality of the wire used was 

 very inferior. 



" I have tried several materials on which to wind the wire, 

 but have fo md nothing thnt answers so well as mica The 

 plan I generally adopt is to double the wire on itself, and wind 

 it round a very thin plate of mica, in such a way that it only 

 touches the mica at the edgts. This method gives very good 

 insulation, even at high temperatures, and, so far as I can 

 discover, the mica has no action on the wire even at temperatures 

 of 1200" C. 



"Another defect of the Siemens pyrometer is the iron-con- 

 taining tube. Metallic vapours of any kind will attack the wire 

 readily, and will ruin the pyrometer. It is not probable that 

 the iron itself will be appreciably volatile at temperatures below 

 1000° C, but it is very likely to contain several more volatile 

 impurities. Vapours of copper, tin, zinc, &c., rapidly render 

 the wire brittle and useless. A comparatively small trace 

 suffices." 



Mr. Callendai's wires were inclosed in glass, a material which 

 naturally cannot be used for high temperatures. He finds that 

 a hard-glazed porcelain tube does very well to protect the wire, 

 at least up to 'empeiatures of 1200° C. A silica tube would be 

 better, but that the author has not succeeded in obtaining. He 

 pointed out, however, that good porcelain is not so fragile as it 

 is generally thought to be. Pie has only broken one tube, and 

 that with a hammer. He hopes, however, ultimately to be able 

 to produce a satisfactory silica tube. The remainder of the 

 paper was taken up with a description of the indicating 

 apparatus, but here, again, we must refer our readers to the 

 original paper. 



Mr. Tnwaites's paper is of far too formidable proportions for 

 us 10 deal with in anything like detail in this notice. He 

 describes calorimeter.-, pyrometers, &c., and their uses. A good 

 deal of the matter put forward is not altogether new. 



Mr. Wmgham's paper on the slide rule is of value to those 

 interested in the practical working of blast furnaces. 



Mr. Wailes's gas furnace valve has been designed to give an 

 absolutely air-tight closing, an effect which is obtained by a 

 water seal. Illustrations were given by means of wall diagrams. 



The meeting was brought to a cljse with the usual votes 

 of thanks. 



The autum 1 meeting will be held in Liverpool, but the date 

 is not yet fixed. 



the yearl v admissions to the ro yal 

 Society.' 



"T^lIE discussions that arose in connection with the revision of 

 the Statutes of the Royal Society during the years 1890 

 and 189 1, led me to endeavour to obtain definite data on which 

 to found a trustworthy opinion as to the efTect of the existing 

 limitation of the number ol yearly admissions on the eventual 

 total strength of the Society, and the probable result of in- 

 creasing the number beyond fifteen, the present limit. 



The facts bearing on this subject, so far as I have been able 

 to collect them from the records of the Society, are embodied in 

 the tables annexed to this co.nmunication, for the proper appre- 

 ciation of the significance of the figures in which a few preliminary 

 explanations are necessary. 



The anniversary of the Society being fixed for November 30 

 in lach year, the customary record of the number of Fellows for 

 any year refers to the number on that date. I have throughout 

 regarded the date to which this number applies as being 

 January i of the following year. 



The annual election of Ordinary Fellows usually takes place in 

 the first or second week of June in each year. I have considered 

 the date to be January i of the same year. 



The lapses, whether from death or other causes, have been 

 treated as having occurred at the end of the calendar year in 

 which they take place. 



These assumptions have been made to simplify the various 



' " On the Probable ElTect of the Limitation of the Number of Ordinary 

 Fellows elected into the Royal Society to Fifteen in each Year on the 

 eve.itu >1 T^tal Number of Fellow^." By Lieut.-General R. Strachey, R.E., 

 F.R.S. Read at the Royal Society on May 12, 1892. This paper was 

 accompan.ed by four tables, presenting su nmaries of the author's results. 



NO. II 79, VOL. 46] 



computations that the investigation required (which have been 

 sufficiently troublesome as it is), and owing to the considerable 

 period dealt with, forty-three years, the results will not, I 

 believe, be sensibly affected thereby. 



Unless it is otherwise specifically stated, the numbers refer ex- 

 clusively to the Ordinaiy Fellows, elected at the regular annual 

 meetings fixtd for the purpose. 



So far as I have been able to ascertain (for the earlier records 

 in many particulars are defective), the number of Ordinary 

 Fellows elected since 1848 has been 15 in each year, except on 

 four occasions ; in two years the number having been 14, and 

 in two years 16 : the average, therefore, is 15 yearly. 



During the period since 1848, the number of Royal and 

 Honorary Fellows has been about 5, and the Foreign Members 

 about 50 ; these are included in the total number of Fellows 

 shown in the annual reports of the Council, but will not be 

 further considered in what follows. 



The rules under which certain privileged classes have been 

 admitted as Fellows, in addition to the Ordinary Fellows, have 

 varied somewhat since 1848, but at present, apart from the per- 

 sons eligible for the classes of Fellows above excluded, the only 

 persons so privileged ate Privy Councillors. The total number 

 of Privileged Fellows elected since 1848 seems to have been 75, 

 which for 43 years gives an average of 175 per annum. 



Table 1. contains a summary of the available data relating to 

 the total number of Fellows since 1848. 



The total number, excluding Royal, Honorary, and Foreign 

 Fellows, at the commencement of 1848 was 768. I am notable 

 to say how many of these were Fellows elected in the ordinary 

 way, and how many were privileged, but this has no importance 

 for my present object. Fiom i860 onwards the distinction be- 

 tween the three classes, those elected before 1848, Privileged 

 Fellows, and Ordinary Fellows, is exhibited. 



At the end of 1890, the total number of Fellows, excluding 

 the Royal, Honorary, and Foieign Classes, was 463 ; of whom 

 26 were Fellows elected before 1848, 36 were Privileged Fellows 

 elected since 1848 ; and 401 Ordinary Fellows elected since 

 1848. 



Hence it appears that the reduction of number of Fellows, of 

 the three classes last referred to, has been 305, and as the num- 

 ber of admissions of the Privileged class has not been very 

 materially affected by the changes in the rules relating to them, 

 it follows that virtually the whole of this large reduction is a 

 consequence of the restriction, to 15, of the number of Ordinary 

 Fellows elected yearly. 



As the ages of the 768 Fellows who constituted the bulk of 

 the Society in 1848 are not known, and as the conditions of 

 election before that year differed materially from what they have 

 been since, no very useful conclusions can be drawn from the 

 rate of their diminution since 1848. 



Assuming, howevei, that the number of Privileged Fellows 

 in 1848 was, as is probable, about 50, there would remain 718 

 Ordinary Fellows, of whom in 43 years 692 lapsed, or at an 

 average yearly rate of 2*24 per cent., that is rather more than 

 16 a year. This rate, as I shall show subsequently, does not 

 differ greatly from that which has prevailed among the Ordinary 

 Fellows elected since 184S, and it may therefore be presumed 

 that the average age of the Fellows in that year did not differ 

 greatly from the average age since. 



Table II. gives, as far as available data admit, the ages at 

 the time of election of all Fellows elected since 1848 ; and 

 shows the number of years they severally survived, the average 

 age at election, the number and average age of those who were 

 alive in 1891, and the greatest and least ages of Fellows elected 

 in each year. 



From this table it will be seen that there has been a gradual 

 small increase in the age at election ; the average for the first 

 10 years having been 42 2 ; for the second 10 years, 43'0; for 

 the third 10 years, 44*8 ; and for the last 13 years, 45-2. 



The accuracy of these conclusions may be somewhat affected 

 by the greater number of unknown ages in the earlier years, the 

 age when unknown having been taken at the average of the 

 group of years in which the election took place. 



The least age at which any Fellow ha> been elected is 24, 

 one such case being recorded. The average minimum at any 

 election is slightly under 30, and the average maximum is 

 rather over d-i, ; one election at an age of 87 is recorded, and 

 several above 70. 



The oldest survivor of the Fellows elected since 1848, who 

 alone are dealt with in this table, was 86 years of age in 1891. 



