April 20, 191 1] 



NATURE 



255 



xxxiii., of T/ie Astrophysical Journal. Feeling dissatisfied 

 with the Crova alcohol actinometer obtained in 1902, Mr. 

 Abbot conceived the idea of constructing a new form of 

 pyrheliometer. This consists of a double walled, large 

 test-tube blackened within, with a stream of water circu- 

 lating between the double walls and absorbing the heat 

 collected inside the chamber. The sun's rays shine into 

 this chamber through a measured orifice, and the heat 

 collected by the water is measured by a system of platinum 

 wires forming a resistance thermometer. 



Test experiments with electrically heated coils, in which 

 the heat could be measured with great accuracy, have 

 shown that the water system collects all the heat intro- 

 duced within I per cent., and that the solar heat can be 

 collected and measured to within 0-2 per cent. Thus the 

 scale of the solar-constant observations of the Astrophysical 

 Observatory is reduced to the absolute scale of calories 

 (15° C.) per square centimetre per minute within a prob- 

 able error of 0-2 per cent., an accuracy hitherto not 

 attained. 



Double-star Observations. Circular No. 6 of the 

 Transvaal Observatory contains a list of about 350 double 

 stars discovered with the 9-inch Grubb refractor of the 

 observatory during 1910. Mr. Innes directs attention to 

 the common statement that the southern heavens offer a 

 practically unexplored field to the would-be double-star 

 discoverer, and shows that this is by no means the case. 

 The circular also contains a list of double stars discovered 

 by Mr. Ward at Wanganui, New Zealand. The list con- 

 tained observations of 212 stars, but has been revised, and 

 in some cases the observations confirmed, by Mr. Innes. 



Nos. 4486 and 4488 of the Astronomische Nachrichten 

 also contain series of double-star measures, the former by 

 Herr J. Voiite at the Leyden Observatory, the second a 

 longer list of micrometer measures by Prof. H. E. Lau 

 at Copenhagen. 



MiCROMETRiCAL MEASUREMENTS OF NeBUL^. A USeful 



catalogue of nebulae lying south of the equator is pub- 

 lished as No. 17 of the Publications of the Cincinnati 

 Observatory. In the preface Prof. Porter explains that 

 when the 16-inch Clark refractor was ready for work at 

 ih',' end of 1904 it was decided to observe those nebulae 

 ol Dreyer's N.G.C. which have southern declinations, and 

 the work has been carried on since. There was no idea 

 of discovering new objects, but seventeen were found, of 

 which nine appear certainly to be novae. The catalogue 

 includes the positions of 66q objects, with the micrometrical 

 measures of them and of the companion stars. 



The Motion of Certain Stars in Space. — As an extract 

 from the Bulletin Astrononiique, we have received a paper 

 in which Prof. Stroobant discusses the question of the 

 sun being a member of a group of stars having a common 

 motion through space. In the result, he finds a fairly 

 -trong indication that the sun does belong to such a 



-rem, which also comprises the stars o Cassiopeiae, 

 Persei, o Persei, a Scorpionis, y Cygni, and e and 

 c I'egasi. 



THE COMPOSITION OF THE GASES CAUSED 



BY BLASTING IN MINES.' 

 'PHE report before us was drawn up for the Govern- 

 ment of Western Australia by Mr. E. A. Mann, the 

 <liief Inspector of Explosives. The importance of investi- 

 Liations on the subject of the composition of gases caused 

 \<v blasting in mines cannot be overestimated, since, hand 

 ill hand with the safety in actual use of blasting explosives, 

 rhore is the possibility of accidents arising from the pro- 

 'Incts of the explosion accumulating in badly ventilated 

 (dings. This risk has been recognised by several 

 ■vernments, and investigations instituted. In the present 

 ■^ a most valuable and suggestive report is the out- 

 ■me. 



Nitroglycerine is the only largely employed explosive 

 which contains more than sufficient oxygen for its com- 



' Report on investigations inio the Composition of the Cises caused by 

 ling in Mines, hy E. A. M.inn, Chief Inspector of Explosives for 

 tern Australia. (Perth : by authority : Fred. Wm. Simpson, Govern- 

 it printer.) 



NO. 2164, VOL. 86] 



plete combustion, and on firing should therefore yield onlj 

 carbon dioxide, nitrogen, water vapour, and an excess of 

 oxygen. The explosives investigated were mainly nitro- 

 glycerin explosives : blasting gelatin (nitroglycerin with 

 approximately 10 per cent, soluble nitrocellulose), gelatin 

 dynamite, and gelignite, both of which contain wood meal 

 and potassium nitrate. Generally speaking, the former 

 contains a slight deficiency of oxygen, whilst the latter 

 two an excess. 



The gases produced on firing under actual working con- 

 ditions were collected by Mr. Mann, who wore for the 

 purpose a Fleuss oxygen apparatus. In all 131 entries 

 were made into the dangerous gases, and analysis invari- 

 ably showed that carbon monoxide, which is so highly 

 poisonous, was produced, together with small quantities of 

 oxides of nitrogen, dangerous by reason of their physio- 

 logical activity. 



An important ratio obtained is that between CO : COj, 

 which is a fair measure of the relative dangers of gas- 

 poisoning with the different explosives. The highest is 

 found with blasting gelatin (i : 6-5), a general average for 

 all the explosives being about 1 : 13. It is well known 

 that pressure on firing exercises an enormous difference 

 in the distribution of oxygen to form carbon dioxide or 

 monoxide, high pressures increasing the CO,, and this has 

 an important bearing in practice. If the explosives men- 

 tioned are fired in a bomb, the maximum oxidation results, 

 since maximum pressure is attained. In a rock, the 

 greater the resistance, either from its character or the 

 position of the charge, the lower should be the ratio 

 CO : COj. The ideal condition would be where the rock 

 only gives just when the maximum pressure is reached ; 

 but this is a condition impossible to realise in practice, so 

 that holes are invariably overcharged, i.e. the rock is 

 blown out before oxidation has been completed, hence the 

 production of carbon monoxide. 



Two very important points are brought out, first, the 

 influence of the paper wrapper of the cartridge, which 

 gives a deficiency of oxygen on the whole charge. Com- 

 parative tests with and without wrappers show that in the 

 case of gelignite the ratio CO : COj has been reduced from 

 I : 16 to 1:51, and in the case of blasting gelatin from 

 1-95 to I : 52. Secondly, the influence of the physical 

 condition of the powder ; where the most intimate mixture 

 of the ingredients is obtained, there is every chance of 

 oxidation proceeding more rapidly to the maxirnum actually 

 obtainable before rupture of the rock. Some excellent 

 coloured plates of the microstructure of many of the ex- 

 plosives under polarised light emphasise the frequent 

 heterogeneity of their structure. 



The effect of fuse firing as compared with electric firing 

 is carefully considered, and everything is greatly in favour 

 of the electrically fired charge, fuses being responsible for 

 much deleterious gas. 



DRAINAGE AND MALARIA. 



T N India, the sanitary expert adviser of the complacent 

 type must either " bend or break " under the weight 

 of official opinion (held as strongly by the youngest Under- 

 Secretary as the veteran F"inancial Member) that the 

 Sanitary Department must be classed financially as " un- 

 productive," and must therefore be, in its representations 

 involving expense, tactfully unobtrusive. Hence, possibly, 

 the unconscious evolution of the policy of " quinine pro- 

 phylaxis," which would relieve the Government of India 

 from applications for loans and " free grants " for radical 

 anti-malarial measures, such as drainage works, requiring 

 the sinking of capital, and would throw upon the in- 

 habitants of malarious areas (who are notoriously 

 impecunious as a sequence of disability to labour) the 

 onus of purchasing an expensive drug — through an in- 

 definite number of years. 



In connection with the letter in Nature of February q 

 by Dr. Bentley — one of the small circle of supporters of 

 this policy — and the reply thereto by Dr. Malcolm Watson, 

 there is now available a record * of facts at issue, which 

 will enable those interested in a question of much import- 



' "The Prevention of Malaria in the Federated Malay States." Bv 

 Dr. .M.-iIcolm Watson, with a preface hy Prof. Ronald Ross, C.B., F.R.S. 

 Pp. '39- (Liverpool: .School of Tropical Medicin , 1911). Price js. 6if. 



