100 



ATMOSPHERE. 



Thoughts on the Influence of Ether in the Solar 

 System: Its Relations to the Zodiacal Light, 

 Comets, the Seasons, and Periodical Shooting 

 Stars, by Alexander Wilcocks, M. D., published 

 iu the Transactions of the American Philosoph- 

 ical Society, vol. xiii., Part I., having been read 

 before the Society named, May 20, 1864; a 

 report On the Right Ascension of the Pole Star 

 at Determined from Observation, by Mr. T. H. 

 Safford, Assistant at the Observatory of Har- 

 vard College ; and, as among papers having an 

 astronomical bearing and read at the meetings of 

 the National Academy of Sciences in January, 

 1864 one by Prof. B. A. Gould, on the Reduc- 

 tion of the Observations of Fixed Stars, made 

 by J. J. Lepaute D'Agelet, 1783-'85, to the 

 Equinox 0/1800 ; one by Prof. B. Pierce, on the 

 Saturnian System ; and one by Prof. S. Alex- 

 ander, on Observations of the Planet Venus 

 near tht Times of her Inferior Conjunction, 

 September 28, 1863, and subsequently ; and 

 also in January, 1865 one by Prof. Pierce, 

 on the Tables of the Moon. 



ATMOSPHERE. It is no longer a new 

 thought that the advance of scientific knowl- 

 edge shows continually more and more how 

 the subject-matters of the various sciences con- 

 nect intimately one with another, and how the 

 investigation of physical problems of apparently 

 the most unlike character so often leads their 

 explorers to a common ground and compels 

 them to appeal to the same class of facts. 

 Thus, the connection of auroras with magnetic 

 phenomena of the earth's surface has come to 

 be well established; and it is stated that ob- 

 servations of M. Quetelet indicate a connection 

 also between the former and the so-called shoot- 

 ing stars. But further, both the phenomena of 

 meteors and of auroras are now likely to be ap- 

 pealed to for the decision of such questions as 

 those of the actual extent of an atmosphere 

 above the earth, the constitution of its upper- 

 most or remotest portions, and the possible ex- 

 istence of a diffused nebular or cosmical matter 

 in space, beyond the limits of all the planetary 

 atmospheres. 



Auroras. For some opinions respecting the 

 height of auroras, &c., with an incidental notice 

 of a pulsating or flaming aurora, see this subject 

 in the volume for 1862. A few facts only under 

 the specific head given, will here receive men- 

 tion. An aurora of great brilliancy notwith- 

 standing the strong light of the moon, then 

 nearly full was witnessed at New Haven, on 

 the night of August 2d-3d, 1865 (American 

 Jour, of Science, September). At l h 45 m A. M., 

 on the 3d, the auroral lights formed a very ex- 

 tensive sheet ; and in this, from about 18 above 

 the horizon, the streamers showed the waving 

 or "flaming" character successive flashes of 

 light quickly following each other, with inter- 

 rupted courses, up toward the corona, and their 

 angular velocity being judged to be about 90 a 

 second. The streamers had a lateral motion in 

 the direction the reverse of that which is most 

 usual ; namely, from west to east. The observer 



whose account we quote had many years pre- 

 viously witnessed a bright aurora at a very 

 early morning hour, and had observed that the 

 upper segments of the streamers presently be- 

 came of a vivid rosy hue, which extended down 

 to about the same altitude in all. He suspected 

 this to be the effect of sunlight striking the 

 tops of the streamers at a height of several hun- 

 dred miles above the earth's surface. Now, 

 the aurora of August 3d, as seen at an early 

 morning hour near and above the constellation 

 Orion, presented the like phenomenon. The 

 streamers here situated, which at 3 h 30 m were 

 of a yellowish white, became at 3 h 40 m of a 

 more intense yellow at the top, with a speedy 

 progress downward; and this was shortly fol- 

 lowed, in succession and in like manner, by a 

 more glistening yellow, and then a clear dilute 

 red or rosy color. The observations at the 

 time, though not very accurate, would indicate 

 about 50 miles' as the height of the group now 

 referred to. The writer further suggests that 

 the abrupt edge or termination below, noticed 

 in so many auroras, may perhaps indicate the 

 "definite upper boundary of the atmosphere 

 proper," at the transition from this lower to 

 some secondary atmosphere, or to ethereal 

 space. 



In an article entitled " The determination of 

 the height of Auroral Arches, from observations 

 at one place" (Amer. Jour, of Science, May, 

 1865), Prof. H. A. Newton concludes that ob- 

 served facts relative to auroras, and especially 

 the constancy of the general form of the arch 

 at different times and places, and its cutting the 

 horizon at points less than 180 from each 

 other, support the hypothesis of Hansteen, that 

 the auroral arch is a real ring, which in its 

 normal form is parallel to the earth's surface, 

 and is symmetrically placed about the magnetic 

 pole. He also concludes that different observers 

 do not see different arches at the same time, 

 but that the curve of the arch has a definite 

 place in the atmosphere. He gives a table of 

 the altitudes and amplitudes in degrees, the 

 height in miles, etc., of twenty-eight auroras, 

 mostly observed by Herrick and Bradley, and 

 at New Haven ; the heights range from 33 to 

 290 miles ; average, 134 miles. The results are 

 to be regarded as only approximately correct; 

 but the method of observations at a single place 

 is recommended as both an auxiliary and a check 

 to those obtained by other methods. 



Question of the Height of the Atmosphere. 

 Some years since, the writer of this notice in- 

 sisted very earnestly and before many auditors 

 upon the fact, evident enough in itself perhaps, 

 that, not less than the fishes, man is the inhab- 

 itant of an ocean ; the most marked differences 

 being that the latter has an aerial instead of a 

 watery ocean to move and live in, and is by his 

 constitution naturally confined to existing at 

 the bottom of his ocean, instead of rising and 

 moving at elevations within it. And it is a 

 pleasure now to observe, in the new and singu- 

 lar assiduity with which all atmospheric prob- 





