726 KANSAS CITY REVIEW OF SCIENCE. 



and the present expedition is to continue the work. The river, he thinks, will 

 rank among the great rivers of the world ; numerous streams flow into it, and it 

 is surrounded by dense forests of spruce and pine and birch, and by a general 

 richness of vegetation unlocked for in so high a latitude. 



The Putnam is not so great a river, however, as the Yukon, which Lieut. 

 Schwatka explored in 1883 fpr 1,800 miles. He crossed the country 150 miles 

 from Sitka in May, to the headwaters of the Yukon, where he built a raft, and 

 floated down the stream, through marshes, deep lakes and great canons, where 

 the water sometimes rushed for five miles between huge basaltic cliffs. The 

 Yukon "is so long," says Lieut. Schwatka, "that if its source were at Salt Lake, 

 its waters might empty into New York Bay, and its mouth is so wide that New 

 York would be on one side and Philadelphia on the other." Another expedi- 

 tion, under Lieut. Abercrombie, attempted last summer to explore the Copper 

 River, which is from 400 to 500 miles long, but did not penetrate it far. 



Of the wisdom and utility of these explorations there can be no question. 

 Alaska is not ice-bound the year through; steamers can get to Point Barrow, the 

 northernmost land, at almost any time, and sailing vessels can reach it in ordinary 

 summer weather. We know the country almost for its fisheries alone ; its im- 

 mense and almost inexhaustible tracts of timber are scarcely touched, and its 

 mineral wealth is almost a matter of speculation. The research should be ex- 

 haustive and more distinctly scientific than it has been ; and it is pre eminently a 

 Government work. — Globe- Democrat. 



COAL-DUST IN COLLIERY EXPLOSIONS. 



Bergrath Althaus, in a recent session of the Natural History Division of the 

 Silesian Society filr vaterlandische Cultur, made an interesting report concerning 

 the work of the Prussian Commission for the discovery of safeguards against fire- 

 damp, in the course of which he called special attention to the effect of coal-dust in 

 aggravating the disastrous effects of explosions. Of the fatal accidents in Prussian 

 coal-mines, Jj- are due to fire-damp ; and the average number of deaths per explo- 

 sion where coal-dust is present is 5, against 1.4 where coal dust is absent. Tbis sta- 

 tistical argument is conclusive as to the importance of a study of the part played 

 by coal-f-ust in such cases. The paper of Mr. Hutchinson, published in the En- 

 gineering and Mining Journal, January loth, 1885, sums up the English inves- 

 tigations of this subject, almost to the present time (we believe one or two import- 

 ant papers have appeared since it was written) ; but it is less full and satisfactory 

 as to what has been done in Europe; and it leaves in doubt the vital questions 

 involved. 



Bergrath Althaus, in the report to which we have referred, says of the Eng- 

 lish investigations, particularly of Galloway and Abel, that "they did not suc- 

 ceed in completely explaining the influence of coal-dust ; and hence opinions on 

 the subject continue to differ." But he remarks, a little farther on, that the 



