194 



SCIENTIFIC NEW^S. 



[Nov. 1st, 1887. 



stronger batch. This, however, should hardly be a matter 

 of surprise, for one would expect that such a process of 

 selection would at once suggest itself as necessary when 

 dealing with a subject of so great importance. 



In England, however, according to our usually well- 

 informed contemporary, no gunpowder maker has yet 

 thought it worth while to incur the expense of a test gun 

 to try his powder with, and partly owing to this fact we 

 find ourselves beaten by the German Company, who not 

 only have a large number of works in Germany and Russia, 

 but who have now established extensive works at Chil- 

 worth in Surrey. As a further instance of the greater care 

 shown by our foreign competitors, we learn that the Ger- 

 man makers of armour plates also have a large gun and 

 testing grounds, where they test samples of every fresh 

 charge of steel made, by actually firing shot against it. A 

 result is that the makers in question have established a 

 deservedly high reputation for the excellence of their manu- 

 facture, and they are able to secure important Government 

 orders. In our opinion this is in no small degree due to 

 the effect of a superior technical education which engenders 

 habits of care, and a keener appreciation of the importance 

 in all cases of accurately testing the results of processes and 

 operations on which success so much depends. 



Whitworth Scholarships. — We learn from the Man- 

 chester Technical School that considerable modifications 

 have been made in the rules under which these scholarships 

 are to be awarded in future. In addition to scholarships, a 

 number of exhibitions are established, according to the 

 following scheme : Twenty ;:^ioo exhibitions, ten ;^5o ex- 

 hibitions, and four scholarships of ;£i25 a year, tenable 

 for three years, will be competed for in 1888; ten ^100 

 exhibitions, twenty ^^50 exhibitions, and four scholarships 

 of ;£i25, tenable for three years, in 1889 ; and thirty _;^5o 

 exhibitions, and four scholarships of _;^i2 5 a year, tenable 

 for three years, in each subsequent year. The competitors 

 who obtain scholarships of ;^i25 a year will be required 

 while holding their scholarships to devote their time entirely 

 to the prosecution of their education as mechanical en- 

 gineers, and before any scholarship can be finally awarded, 

 the scholar must state, for the approval of the Department, 

 precisely how he proposes to spend his time during the 

 tenure of the scholarship, and that he will pursue such a 

 course of work or study as is approved or required by the 

 Department. No scholar will be permitted to take any 

 place of profit, or continue in any business he may be en- 

 gaged in when he obtains his scholarship, except under 

 very exceptional circumstances. No candidate can obtain a 

 Whitworth Scholarship twice, and no Whitworth Scholar is 

 eligible to compete for a Whitworth Exhibition. A copy of 

 the revised rules, issued with the new syllabus, can be ob- 

 tained at the Manchester Technical School. 



localities, but we now learn from Germany that the result 

 of some recent experiments shows that the extent of the 

 variation is greater than has been hitherto supposed. It 

 appears that Herr W. Hempel arranged for samples of air 

 to be collected simultaneously at Dresden, Bonn, Cleveland, 

 U.S., Para, and Tromsoe. Collections were made daily 

 from ist April to i6th May of last year, and all the samples 

 were carefully analysed. The mean percentage of oxygen 

 was 20'93, but it was as high as 2i'o on 22nd April at 

 Tromsoe, and as low as 20'86 on 26th April at Para. The 

 averages for all the places of observation were, 20 92 at 

 Para and Bonn, 20-93 at Cleveland and Dresden, and no 

 less than 20-95 at Tromsoe, thus showing that during the 

 period of trial the air was richer in oxygen towards the 

 north. 



The proportion which the nitrogen of the air bears to 

 the total volume of the air remains practically constant, but 

 the proportion of oxygen varies with the amount of carbonic 

 acid avid the organic impurities present in the air. If, 

 therefore, the percentage of oxygen is high, it may be 

 assumed that the air is relatively free from impurities, and 

 for this reason Tromsoe may be said to have the purest 

 air of all the places tried. Such a variation in the proportion 

 of oxygen as is here given would of itself have little or no 

 effect physiologically on the human being, but as an index 

 of the comparative freedom from impurities in different 

 places it is of very great importance. We regret to say 

 that the injurious effect of organic impurities in the air is 

 too little understood or thought of by people generally. 

 The subject is, however, one of great importance, and if 

 our theatres, churches, and other places of public resort 

 were more thoroughly ventilated there would be fewer 

 organic impurities, and consequently fewer sufferings from 

 headaches and malaise. It would be very instructive if 

 samples of the air breathed in our public buildings when 

 filled with an audience were systematically collected and 

 analysed, and if some really competent man of science were 

 to take charge of the investigation. 



Oxygen of the Air. — It has long been known that the 

 proportion of oxygen in the air varies slightly in different 



The Longevity of Working Men. — Those who are 

 familiar with the working of life insurance offices are 

 aware that to a certain extent averages are worked out for 

 the probable duration of lives in different professions, but 

 the Berliner Zeihmg has made a much more elaborate clas- 

 sification after collecting statistics of the lives of all who 

 are engaged in industrial pursuits in Germany. From 

 these returns it appears that the lifetime of the gardener, 

 the mariner, and the fisherman averages 58 years ; that of 

 the baker, the brewer, and the butcher, 54 years ; the 

 carpenter, the bricklayer, and the painter, 49 ; the lock- 

 smith, the blacksmith, and the cabinet-maker, 47 years ; 

 the shoemaker and the tailor, 44 years ; that of the stone- 

 mason, the sculptor, the compositor, and the lithographer, 

 41 years ; and the common labourer, 32 years. In the 

 learned professions the following averages are assigned : — 

 The lifetime of ministers of religion is set down at 67 



