POPULAR MISCELLANY 



123 



whom 630 were iu Cincinnati, 549 in New 

 York, and SOO in Brooklyn. Of the 630 

 Cincinnati pupils, 209 were from the dis- 

 trict-schools, and of these 83 1 per cent, 

 had natural, or emmetropic eyes, while 10 

 per cent, were near-sighted. In the inter- 

 mediate schools, 210 scholars were exam- 

 ined, and of these 80 per cent, were natural, 

 and 14 per cent, near-sighted. In the nor- 

 mal high-schools, the eyes of 210 students 

 were examined, and of these 78 per cent, 

 were emmetropic, and 16 per cent, near- 

 sighted. All this goes to show that near- 

 sightedness is a progressive disease in the 

 schools. The results for the other two 

 cities teach the same lesson. 



The 549 students mentioned above as 

 examined in New York belonged to the New 

 York College. Here, in the introductory 

 classes, SVi per cent, were found emme- 

 tropic, and 29 per cent, near-sighted. In 

 the freshman class 421 per cent, had natu- 

 ral eyes, and 40 per cent, were near-sighted. 

 In the sophomore class no very material 

 difference from what was observed in the 

 preceding classes ; but in the junior class 

 37 per cent, had natural eyes, and 56 per 

 cent, were near-sighted. In the senior class 

 50 per cent, had normal eyes, and 37 per 

 cent, were near-sighted. The Brooklyn 

 students examined belonged to the Poly- 

 technic Institute of that city. Here, in the 

 o.cademic department, 56 per cent, were 

 emmetropic, and 10 per cent, near-sighted. 

 In the collegiate department ( a higher 

 grade), 53 per cent, were emmetropic, and 

 28^ per cent, were near-sighted. 



Astronomipal Observations on the Rocky 

 MoantainSi It is stated by Prof Henry 

 Draper, in the February number of the 

 American Journal of Science, that, during 

 two years when he photographed the moon 

 every moonlight night at Hastings-on-the- 

 Hudson, there were only three occasions 

 when the air was still enough to give good 

 results. Out of 1,500 lunar negatives, only 

 one or two were really fine pictures. 



Last summer, during a trip to the Rocky 

 Mountains, he took with him a small achro- 

 matic, hoping to find more steadiness of 

 the atmosphere at great elevations, but was 

 disappointed. At Salt Lake City, 4,650 

 feet above the sea, Capella twinkled as bad- 



ly, both to the naked eye and in the tele- 

 scope, as he ever saw it at the sea-level. 



At Fort Steele, near 7,000 feet eleva- 

 tion, Antares twinkled very much ; and at 

 Camp Douglas, 5,250 feet above the sea, 

 the twinkling of several stars examined 

 was surprisingly great. 



At one point, however, he found the at- 

 mosphere without undulations, and the stars 

 shone through it with a steady light. The 

 central disk of Arcturus, he says, was hard 

 and sharply defined ; Antares near setting 

 hardly twinkled at all ; the moon was per- 

 fectly steady. 



This point of observation was not far 

 from Fort Steele, in the main range of the 

 Rocky Mountains, at an elevation of 8,900 

 feet above the sea. Distant objects seemed 

 near in the transparent air. The sky was 

 not black, as he expected, but of a light 

 blue; the moon, however, was near its full. 



Another trial was made at Trout Lake, 

 nearly 10,000 feet above the sea-level, and 

 the air was found to be unsteady but trans- 

 parent. At this point, however, intense cold, 

 fierce winds, and heavy snow-falls, occur, 

 making the location of an observatory here 

 undesirable. 



Dr. Draper concludes that the atmos- 

 phere in these high regions, although more 

 transparent, is quite as tremulous as at the 

 ocean-level at New York. 



luflaence of Heat on Galvanic Condnc- 

 tivityi Till very recently it was held to be 

 a law of Nature that the galvanic conduc- 

 tivity of all metals and metalloids is dimin- 

 ished by rise of temperature. It has been 

 shown, however, that selenium is an ex- 

 ception to this rule, its conductivity being 

 increased by heating. And now a further 

 exception must be made in the case of 

 tellurium, a body closely allied to selenium. 

 We have already (in vol. x., p. 115) given 

 an account of Siemens's researches on the 

 action of light on selenium ; we now present 

 a synopsis of the results obtained by Franz 

 Exner in his experiments with tellurium. 

 Three bars of tellurium were prepared. 

 Bar 1 broke before its dimensions were 

 determined ; bar 2 was 54 millimetres in 

 length and 2.6 millimetres diameter; bar 3 

 was 153 millimetres in length and 3.73 mil- 

 limetres diameter. Bar 1 was heated to 200 



