November 27, 1891.] 



SCIENCE. 



305 



Thus, in case of the Fohn wind, for this air to arrive in the 

 valley at a temperature 60° F. above the temperature normally 

 found there, it must have been heated 60° above the temperature 

 normally found at the summit of the mountains from where it 

 started, and it then remains with Dr. Hann to explain how this 

 air acquired the abnormally high temperature before it commenced 

 to descend, and until he has done this he can have no right to 

 claim that he has added one particle towards the explanation of 

 the phenomena of the Fohn; and, even if he was able to get over 

 this difficulty, it still remains for him to explain the phenomenon 

 of the sand-dust, before it can be recognized that the birthplace 

 of the Fohn is anywhere but in the Desert of Sahara. 



The phenomenon of cool night wind from the mountain and 

 the accompanying higher temperature on the mountains than in 

 the valleys find a ready explanation from the same premises. 

 During clear nights the air nearest the earth's surface gets abnor- 

 mally cooled through radiation, and the radiation is more intense 

 on the mountains than on the plains. The cool contracted air 

 will run oEf the slope of the mountain and accumulate in the 

 valleys, while its place on the mountain-side is immediately taken 

 up by air which has not as yet been cooled down by radiation. 

 In the valleys the temperature gets lower than on the mountains, 

 or the plains, because the cooling efifect of radiation is there act- 

 ing upon air which has previously been cooled considerably down 

 by radiation on the mountain, and it is clear that the temperature 

 must sink lower when radiation is acting upon air already cooled 

 ■down, than when the temperature of the air was higher to start 

 with. 



The present writer has, on several occasions, tried to induce so 

 able and prolific writer as Professor Hazen to attack his views for 

 the sake of an argument, but the professor seems to decline to 

 enter upon a discussion with any body who does not belong 

 to the " meteorological camp," as be calls it. Now, be it 

 said, in all kindness, that in our advanced age every body seems 

 to be entitled to express his opinions on any scientific subject 

 when he feels himself convinced of having found something new 

 which may add to the progress of science, and also be entitled to 

 a fair hearing; but be it said, as my impression when I acciden- 

 tally arrived in the meteorological camp, all the inmates seemed 

 to have decamped previously, leaving no one behind to shake 

 hands with me; and this I thought a little discouraging. Dr. 

 Hann may be a most excellent director of the Hohe Warte, and 

 it may seem not a little reckless for an outsider to attack his the- 

 ories; but it should be remembered that even a blind man may 

 sometimes find a seed, — although a civil engineer of high train- 

 ing may not be entirely blindfolded, — and if there be any truth 

 in the maxim of Dr. Hann's countryman, Feuerbach, "that no 

 philosopher ever yet occupied a professorial chair in philosophy," 

 80 it might possibly be equally true that no philosopher in meteorol- 

 ogy ever yet sat on Hohe Warte, however great his attainments as 

 director or weather forecaster might have been. 



Franz A. Velschow, C.E. 



Brooklyn, Nov. 9. 



Auroral Phenomena. 



As Dr. Veeder has mentioned in his description of the aurora 

 of Sept. 9, in Science for Nov. 6, some phenomena not ordinarily 

 accompanying auroral displays that were also visible here, some 

 notes made at the time may be of interest. 



The aurora on that evening was unusually fine, probably the most 

 brilliant observed in four years. It began about 7 40 p.m. as a faint 

 arch five degrees above the northern horizon, which gradually be- 

 came higher until a maximum height of eight degrees was reached 

 at 8.15 P.M. Shortly before this time two smaller arches appeared 

 beneath the principal arch, and soon afterward the ends of the 

 three joined together, forming a serpentine band. This band at 

 8.30 P.M. broke up into brilliant streamers, which were constantly 

 changing in appearance and length, alternately fading and be- 

 coming bright again. 



This continued until 8.50 p.m , when the display reached its 

 maximum brightness and the streamers their greatest length. 

 The elevations of the ends of the streamers above the horizon were 



measured with a theodolite at times, the highest being at a height 

 of 56", though many exceeded 45°. 



Between 9.15 and 9.30 p.m. the aurora diminished greatly in 

 brightness, and at 9.25 two bands extended toward the zenith 

 from the east and west respectively, joining together at 9.37, 

 forming the narrow band that Dr. Veeder saw. This band was 

 apparently of a uniform brightness, approximating that of the 

 Milky Way, and continued, through the period of minimum 

 brightness of the aurora, from 9.25 to 9.35 P.M. After 9,35 p.m. 

 the aurora became brighter, and was visible at 11.40 p.m. 



This band of light was seen at Nashua, N.H., and in this vi- 

 cinity, while the aurora has been reported as visible at several 

 places in Europe as well as America. 



A similar band of light, extending through the zenith from 

 opposite sides of the horizon, was observed during the aurora of 

 May 20, 1888, which was described in Science by several observers 

 during the succeeding month. 



Five auroras were visible during September four of which oc- 

 curred on the 7th, 8th, 9th, and 10th, respectively, — an unusually 

 large number for such a short period of time. 



S. P. Fergusson. 

 Blue Hill Observatory, EeadTille, Mass., Nov. SO. 



AMONG THE PUBLISHERS. 



D. C. Heath & Co., Boston, will soon publish Business Law, 

 prepared by Alonzo P. Weed. This is not only a text-book for 

 business colleges and the business courses of schools and acade- 

 mies, but it is desirable for the desk of the business man. 



— Charles F. Lummis, a Harvard man, who has lived for many 

 years in New Mexico, begins in the Christmas Scribner a group 

 of articles on that little-known territory, with its population of 

 Pueblos, Mexicans, Navajos, and Americans. The articles will 

 be illustrated from the author's own photographs, which are un- 

 usual in subject and variety. 



— The October number of the " Papers of the American His- 

 torical Association" contains six articles. The first is a brief 

 account of '' Slavery in New York " under the colonial govern- 

 ment. Then follow two papers on certain aspects of our national 

 Constitution, the one on " Congressional Demands upon the Ex- 

 ecutive for Information" being the most suggestive. The next 

 is " A Plea for Reform in the Study of English Municipal His- 

 tory," and there is also a longer article on the " Yazoo Land 

 Companies," giving an account of a gigantic land speculation of 

 a century ago, in which political intrigue played a prominent 

 part. But the article that will be likely to interest the greatest 

 number of readers is that on " The Lost Colony of Roanoke," by 

 Stephen B. Weeks. The colony planted by Raleigh on Roanoke 

 Island has always been supposed to have perished; but in 1885 

 Mr. Hamilton McMillan of North Carolina advanced the theory 

 that the colonists retreated inland, where they ultimately inter- 

 married with some friendly Indians, and that the Croatan In- 

 dians, now living in the western part of the State, are their de- 

 scendants. The evidence for this theory in the physique, the 

 traditions, and the names of those Indians is really quite striking; 

 and persons interested in our early history will like to read Mr. 

 Weeks's paper. 



— A second edition of "Modern American Methods of Copper 

 Smelting," by Dr. E. D. Peters, Jun., has just been published by 

 the Scientific Publishing Company of this city. The book has 

 met with great success, the demand for it having long since ex- 

 hausted the first edition. The entire book has been practically 

 rewritten, and new chapters have been introduced on the electro- 

 lytic assay of copper, the smelting of copper with gas in regen- 

 erative furnaces, and the smelting of copper-nickel ores in water- 

 jackets. Additions of great importance have also been made to 

 the chapter on reverberatory smelting, and this portion of the 

 work has been illustrated by nine full sized pages, which form 

 what is said to be the most complete set of detailed working draw- 

 ings of the kind ever published. The arrangement of the book 

 has been improved ; and in addition to the full alphabetical index 

 at the end, a detailed table of contents has been prepared that will 

 be a great aid to the reader. The author has brought a riper ex- 



