570 



SCIEXGE. 



[Vol. VII. , No. 177 



four miles and a half (7.500 metres). They are dis- 

 tributed as follows : in France, 144 ; Italy, 78 ; 

 Switzerland, 471 ; Austria, 462. Their total super- 

 ficial area is between five hundred and a thousand 

 square miles. The longest is the Aletsch glacier 

 in Austria, measuring over nine miles. 



— Dr. Freire of Rio de Janeiro, in a letter to the 

 Louisiana state board of health, thus speaks of 

 the results of his inoculation for yellow-fever : ' ; I 

 have performed over seven thousand inoculations 

 with full success. The immunity was almost ab- 

 solute, notwithstanding the intensity of the epi- 

 demic this year. More than three thousand per- 

 sons who were not inoculated died of yellow-fever ; 

 while among the seven thousand inoculated, in- 

 habiting the same infected localities, subject to 

 the same morbid conditions, but seven or eight 

 individuals, whose disease was diagnosed as yel- 

 low-fever, died." 



— During the year 1885 there were 246 earth- 

 quakes, according to the statistics of C. Detaille, 

 as given in the June number of Astronomie. The 

 largest number of these, 49, occurred in January : 

 the smallest, 11. in October. For the other 

 months the numbers are as follows : February, 

 18 : March, 15 : April. 19 : May, 14 ; June. 29 ; 

 July, 23 : August, 13 ; September, 16 ; November, 

 16. Only 6 are given for North America, as fol- 

 lows : Jan. 12, Washington ; Jan. 18, New Hamp- 

 shire, Carolina ; Jan. 26. California ; Feb. 5, 

 Virginia : Nov. 19, California. 



— A. Raggi has published some observations on 

 the intermittent variation in sound-perception in 

 the human ear, instances of which are probably 

 familiar to many persons. In deep stillness, if 

 one listens to a faintly heard sound, like that of 

 the ticking of a watch, it will be noticed that at 

 irregular intervals the tones are wholly inaudible, 

 while at other times they are distinctly recognized. 

 Mr. Raggi ascertained, by experiments on differ- 

 ent persons, that the intervals of silence usually 

 varied between seven and twenty-two seconds ; 

 while the periods of sound-perception were be- 

 tween seven and eleven seconds in duration, with 

 a maximum of fifteen. He also found that the 

 variation was not due to extraneous sounds, nor 

 to the blood-circulation or respiration, and con- 

 cludes that it results from the inability to keep 

 the attention for long periods at a sufficient de- 

 gree of tension for the perception of faint sounds, 

 or possibly to a variable physiological receptivity 

 in the auditory nerves. 



— A legacy of some $75,000 has been left to the 

 Jena university to be applied in zoological research 

 on the basis of Darwin's evolution theory. The 

 testator is Heir Paul von Ritter of Basle, who be- 



lieves the teaching of Darwin to be the greatest 

 sign of progress which the century has yet given. 



— According to the statistics recently published 

 by the minister of agriculture and commerce, it 

 appears that the quantity of olive-oil produced 

 last year, in the various provinces throughout 

 Italy, was 52.34 per cent below the average annual 

 yield, which is calculated at 3,405,500 hectolitres 

 (74,921,000 gallons), it being only 1,782,400 hecto- 

 litres (39,212,800 gallons; ; 11 per cent of this total 

 amount was of superior quality, 73 per cent good, 

 and 16 per cent mediocre. 



— The Royal academy of medicine of Belgium 

 has recently offered its largest prize ($5,000) for 

 the most meritorious work or paper on the treat- 

 ment of diseases of the nervous centres, especially 

 for a remedy for epilepsy. The great need of 

 some better means of controlling this last disease 

 induced the academy to offer an additional prize 

 of si, 600 for the best paper on that subject. The 

 prizes are international, and will be awarded in 

 December, 1888. 



— Late deep-sea explorations in the Atlantic, 

 carried on under the auspices of the London geo- 

 graphical society, have shown that the ocean- 

 bottom in the northern region is formed of two 

 valleys, of which one, in width, reaches from the 

 tenth degree of east to the thirtieth of west longi- 

 tude, extending to the equator, at a depth of not 

 less than thirteen thousand feet. The other lies 

 between the thirtieth and fiftieth degrees of west 

 longitude. The mountain - chain separating the 

 two valleys extends northwards towards Iceland, 

 and southward to the Azores, and is of a volcanic 

 character at its ends. Its greatest breadth is a 

 little less than five hundred miles. 



LETTERS TO THE EDITOR. 



*♦* Corresi>ondents are requested to be as brief as iJossible. Tlie 

 writer's name is in all cases required as proof of good faith. 



Is the ocean surface depressed ? 



Do barometric observations give any bint regard- 

 ing the depression of the sea 'at the ceDtre of the 

 oceans ' ? 



If, as is maintained, there be a depres>ion of a 

 thousand metres, the barometer should show about 

 three inches and a half more pressure at the centre 

 of the oceans than at what we ordinarily call sea- 

 level. 



Were there any barometric observations made on 

 the islands where the pendulum was swung j or do 

 barometric observations made on any of the oceanic 

 islands cast any light ou this subject ? I have no 

 authorities at hand to consult, or would not ask the 

 question. W. B . S. 



Candelaria, Nev., May 25. 



The notion that there exist in the sea-surface of the 

 earth elevations and depressions amounting to sev- 

 eral hundred metres has recently gained a much 



