554 



SCIENCE 



[N. S. Vol. XXV. No. 640 



tion of the types of tis own genera. It is 

 my opinion that Linnaeus's rules were fol- 

 lowed to a larger extent by his disciples and 

 immediate followers than we are wont to 

 recognize. But the types of Linnsean genera 

 in ornithology are not now a source of trouble. 

 With the exception of two or three, of which 

 VuUur is one, they have long been settled in 

 a way to meet general approval. I do not 

 apprehend that Dr. Stiles meant to suggest 

 that any of these cases should be reopened if 

 it is found that they were not settled in 

 accordance with Linnseus's own rule. Indeed, 

 his later remarks (quoted above) seem to pre- 

 clude such a suggestion. 



In stating the results of my determination 

 of types by the two methods, as given above, 

 it is impracticable to show the steps by which 

 they were reached; I shall, however, publish 

 soon elsewhere not only the basis of th6se 

 results, but a complete list of all the North 

 American genera and subgenera, with . their 

 types by both methods, where the results 

 differ; and also showing each step in the 

 process of elimination for all the genera to 

 which elimination is applicable. 



J. A. Allen 



American Museum of 

 Natural History, New York 



CURRENT NOTES ON METEOROLOGY AND 

 CLIMATOLOGY 



CUMULUS CLOUDS OVER THE SAN FEANCISCO FIRE 



Mention was recently made in these notes 

 of an observation recorded in Nature of 

 cumulus clouds which formed ove" the fire 

 succeeding the San Francisco earthquake of 

 last year. Attention was at the time called 

 to the fact that this was the first, and only, 

 mention of such clouds which seems to have 

 found its way into print. The publication of 

 that comment in Science brought to the com- 

 piler of the notes a letter from Professor 

 George D. Louderback, of the University of 

 California, with reference to the clouds ob- 

 served by him on the same occasion. As the 

 matter is of some general interest. Professor 

 Louderback's letter is here inserted, with the 

 permission of the writer. 



From your review of Mr. Van Norden's descrip- 

 tion of a cumulus cloud over San Francisco at 



the time of the great fire, and your noting that it 

 is the only reference to that phenomenon you had 

 seen, I have concluded that you may be interested 

 in a corroborative observation of mine on the same 

 occasion. I was in Nevada at the time of the earth- 

 quake, and as my parents and other near rela- 

 tives lived in San Francisco I took the first train 

 for that city, but on arriving at the Oakland pier 

 the morning of the nineteenth I found that no one 

 was permitted to cross by the ferries in that di- 

 rection. I spent several hours on the water front 

 looking for a launch that would take me over, and 

 then had a slow trip across the bay and arrived 

 in San Francisco about five o'clock in the after- 

 noon. 



The form of the rising column of smoke im- 

 pressed me very strongly, and I have made a num- 

 ber of efforts since to find some one who might 

 have taken an expressive picture of it, but so far, 

 without success. The dark smoke rising from a 

 large area of the city rather quickly gathered it- 

 self together and rose to a great height as a tall 

 column with a low conical base. At the top it 

 spread out in a practically horizontal layer and 

 drifted slowly to the northwest, in which direction 

 its limit was beyond the range of vision. In fact, 

 the first visible indication that I had of the fire 

 was this drifting smoke cloud beyond the coast 

 mountains seen from the train at Benecia (north 

 of San Francisco ) , and looking west along the gap 

 of Karquinez Straits. 



This horizontal cloud extended a very short dis- 

 tance to the south of the main column — probably 

 not greater than the thickness of the column. 

 Rising above its upper surface and directly over 

 the vertical shaft of smoke was the cumulus cloud, 

 its upper surface forming four or five beautifully 

 regular and pure white domes. Not only was it 

 differentiated from the rest of the visible floating 

 material by its form and position, but distinctly 

 by its color and luster, and I decided that the 

 cumulus cloud was of pure water particles, un- 

 contaminated with the smoke particles that gave 

 their character to the horizontal stratum. I 

 watched it, at intervals, for several hours and 

 noticed but little change. It reminded me very 

 strongly of the photographs I have seen of vol- 

 canoes in eruption, and especially suggested the 

 stone pine of Vesuvius. Even the form of the 

 volcanic mountain was presented to the eye in the 

 conical spreading base of the smoke column. 



As we approached the city the lowering sun was- 

 veiled by the cylinder of smoke, and later by the 

 lower layers, and produced the most striking and 

 weird absorption effects. It became a deep fiery- 



