February 19, 1886.] 



SCIENCE. 



161 



site of the ancient Lake Moeris in Egypt have 

 been so fruitful that the Egyptian government has 

 taken the matter in hand, and it is believed, that, 

 by a small expenditure, the surplus waters of Bahr 

 Yuss'ef can be directed into the now dry depres- 

 sion. Preliminary surveys are in progress to de- 

 termine the practicability and expense of restor- 

 ing a state of things very exactly described by 

 Herodotus, Strabo, and Pliny, as having existed in 

 past ages. 



Ancient Arabic inscription in the Sahara.— 



Le Chatelier furnishes an account of what may 

 prove to be an important inscription in an artifi- 

 cial cavern at Timissao, near the wells and on the 

 right bank of the wady of the same name, in the 

 Sahara. The wady, coming from the south, turns 

 here toward the west. Its banks are of conglom- 

 erate, in two horizontal beds, separated by a bed 

 of gray schist in vertical layers. These schists 

 have been dug out for a distance of over two hun- 

 dred feet, forming a sort of gallery fifteen feet 

 wide and six or seven feet high. The inner wall 

 of the gallery is occupied by an inscription in Tifi- 

 nakh lettering, the characters incised, and painted 

 with red ochre. A more modern inscription in 

 Arabic is simply painted on the roof. At the 

 further end are some archaic incised figures on the 

 wall, including those of five horses. The accounts 

 seem to be truthful, though derived from the na- 

 tives ; and, if so, the deciphering of the inscrip- 

 tions would be of great interest. 



ASTRONOMICAL NOTES. 



Eclipse of the sun, 1886. Aug. 28-29. — ^ Dnl lias 

 been introduced in congress, by Mr. Thomas of 

 Illinois, to enable the secretary of the navy to fit 

 out an expedition to observe the total eclipse of the 

 sun which occurs on the 29th of August next. The 

 sum of ten thousand dollars is appropriated for 

 defraying the expenses of the expedition ; and the 

 secretary is authorized to detail a naval vessel to 

 transport the party to a point near Benguela, on 

 the west coast of Africa, almost the only seaport 

 which is near the central line of totality. The bill 

 was introduced in the house of representatives on 

 the 11th of January, but has not yet come up for 

 consideration A similar bill introduced in the 

 senate has been favorably reported by the com- 

 mittee on naval affairs. It will be remembered 

 that tins eclipse is of rather more than ordinary 

 interest on account of the long duration of 

 totality, — 4 m 41 s near Benguela. Another interest- 

 ing circumstance has been noticed by Dr. Herz of 

 Vienna, in the fact that at totality two stars, 47p 

 Leonis and 49 Leonis, are close to the sun, the 

 latter within the corona. It is suggested, that, by 



means of measurements upon these two stars, 

 something may be learned in regard to the re- 

 fracting power of this peculiar atmosphere of the 

 sun. The total phase will be visible in the West 

 Indies ; but the sun will not be in a good position 

 for observation. According to Nature, at Car- 

 riacou, the largest of the Grenadine Islands, 

 totality commences at 19 h ll m 45 s local mean 

 time, and lasts 3 m 21 s ; the sun's altitude being 

 20°. 



Comet 1886 . . . (Barnard). — According to 

 an ephemeris published by Mr. H. V. Egbert of 

 the Dudley observatory, we may look for this 

 comet to become quite a bright object during the 

 early morning-hours in the latter part of May. 

 Mr. Egbert's calculation shows that the comet on 

 the 20th of May will be 360 times as bright as it 

 was when discovered by Mr. Barnard, Dec. 3. Its 

 position wiU be R. A., 2 h 53 m ; decl., + 20° 26 : 

 that is, it will appear above our horizon about an 

 hour before the sun. 



ST. PETERSBURG LETTER. 



The last number (9) of the Journal of the Rus- 

 sian physico-chemical society contains an elaborate 

 paper, by K. Kraewitch. on the relation between 

 the elasticity and density of the air in a rarified 

 condition. His experiments on the velocity of 

 sound show, that at a temperature of 17.5° C, 

 the velocity decreased from 330 metres, at a 

 pressure of 761 millimetres, to 171 metres, at a 

 pressure of 2.6 millimetres. At a pressure of 280 

 millimetres, the velocity is about the same as the 

 mean air pressure ; but it diminishes rapidly be- 

 low 280 millimetres. He concluded that gases 

 below this pressure do not obey the Boyle-Mari- 

 otte law. 



At the general meeting of the physico-chemical 

 society in December, the coming eclipse of Aug. 

 18, 1887, was discussed. Prof. S. P. Glasenap 

 showed a map on which the path of the total 

 eclipse was marked. As it traverses an immense 

 extent of Russia from Kiev to south-eastern 

 Transbaikalia, and appears also on the shores of 

 the great ocean at Possiet harbor, and as a total 

 eclipse will not appear in Russia for thirty- six 

 years after 1887, he concluded that the best use 

 should be made of the opportunities offered by 

 the eclipse to study different problems relating to 

 solar physics. Prof. N. G. Egoroff followed with 

 a communication on the corona and the opportu- 

 nities offered by the eclipse for its study. The 

 last paper was by Prof. A. Woeikof , on the mete- 

 orological side of the question. Observations on 

 the amount of cloud prevalent in the region show 

 a cloudiness of about 51 ; that is. half the sky is 



