38o 



THE POPULAR SCIENCE MONTHLY. 



and the mountain-sickness for a time dis- 

 appeared. Immediately on inhaling the 

 oxygen there was a disagreeable dazzling, 

 and at one time, after three inspirations, he 

 became giddy and fell off his chair, but 

 soon recovered. The author also describes 

 the effects on himself of breathing a super- 

 oxygenated mixture. With a mixture of 

 45 per cent., he could bear without injury 

 a pressure of only 338 millimetres, which 

 corresponds to the height of Chimborazo ; 

 and with 63 per cent, he was able to stand 

 250 millimetres (less than ten inches), and 

 would have gone farther if his machine had 

 been sufficiently strong. Since M. Bert's 

 experiments, Messrs. Croce-Spinelli and Si- 

 vel have made a balloon-ascension to the 

 extraordinary height of about 26,000 feet. 

 They carried up with them a supply of 

 oxygen, and, by using this after the manner 

 indicated by M. Bert, they were enabled to 

 live without inconvenience in an atmos- 

 phere of extreme rarity. 



Lake Superior Gold-3Iines.— Mr. Peter 

 McKellar lately read, at the Toronto Insti- 

 tute, a paper on the gold-mines of Lake Su- 

 perior. Some Indians from the vicinity of 

 Thunder Bay, in ISTl, brought to Mr. Mc- 

 Kellar, at Fort William, several specimens 

 of quartz, from an examination of which he 

 was led to think that valuable gold-mines 

 existed in the locality. The paper then de- 

 scribed the lodes that had been discovered. 

 The first was the Jackfish Lake lode, which 

 lies about eighty miles west of Thunder Bay. 

 From this lode 126 pounds of ore were sent 

 to the Wyandott Smelting -Works, and 

 yielded at the rate of $500 per ton ; of this 

 sura, $40 was derived from silver, and the 

 remainder from gold. The Partridge Lake 

 lode, lying about 100 miles northwest of 

 Thunder Bay, yielded about $30 per ton of 

 ore. In the summer of 1872 another lode, 

 called the Heron Bay lode, was discovered, 

 about 150 miles northeast of Fort William. 

 It was similar to the Jackfish Lake lode, 

 excepting that its yield of gold and silver 

 was not so great. Mr. McKellar holds that 

 these mines might be worked very economi- 

 cally, and that they would yield as large 

 profit as, if not larger than, any others in the 

 world. In the lodes already discovered, 

 the gold was found very evenly distributed 



through the ore, which is said to exist in 

 large quantities. Iron, lead, and other met- 

 als, occur in the neighborhood. The diffi- 

 culties in developing these mines have been 

 very great, owing principally to the un- 

 settled state of the country. The Indians 

 have refused to help in working the mines 

 until some settlement shall be come to with 

 them, as they fear that white men may 

 come and dispossess them. 



Researches on the Zodiacal Light.— 



Prof. Arthur W. Wright, of Yale College, 

 who for upward of a year has been closely 

 investigating the zodiacal light, has, by 

 means of an apparatus of his own contriv- 

 ing, succeeded in demonstrating that this 

 light is polarized. In the American Jour- 

 iial of Science^ for May, Prof. Wright de- 

 scribes his polariscope, and the results at 

 which he has arrived in the course of his 

 researches. He finds that the plane of 

 polarization of the zodiacal light passes 

 through the sun. In no instance, when 

 the sky was clear enough to render the 

 bands visible, did their position, as deter- 

 mined by the observations, fail to agree 

 with what would be required by polariza- 

 tion in a plane through the sun ; not the 

 sUghtest trace of bands was ever seen when 

 the instrument was directed to other por- 

 tions of the sky. 



Having thus determined the fact of po- 

 larization, the next step was to ascertain 

 what percentage of the light is polarized. 

 For this purpose, the author again had to 

 devise novel apparatus. The amount of 

 polarization was determined to be, " with a 

 high degree of probability, as much as 1 5 

 per cent., but can hardly be as much as 20 

 per cent." 



The fact of polarization implies that the 

 light is reflected, either wholly or in part, 

 and is thus derived originally from the sun. 

 The spectrum of the zodiacal light is not 

 perceptibly different from that of sunlight, 

 except in intensity. The author adds : " A 

 particular object in these observations was 

 to determine whether any bright lines or 

 bands were present in the spectrum, or 

 whether there is any connection between 

 the zodiacal light and the polar aurora." 

 The results give a decidedly negative an- 

 swer to this question. " This is important 



