82 



SCIENCE. 



[Voi,. V., No. 103. 



eluding Gaulard, Gibbs, and Tresca, established a 

 circuit between the station of Lango and intermedi- 

 ate stations, — a circuit of which the total length was 

 80 kilometres (about 50 miles). The wire was of 

 uncovered chrome bronze 3.7 millimetres in diame- 

 ter. The current was produced by a Siemens alter- 

 nating machine of the thirty-horse power type. New 

 forms of secondary generators devised by Gaulard 

 and Gibbs enabled the following different types of 

 electric lighting to be maintained : 1°. At the expo- 

 sition building, 9 Bernstein lamps, 1 Soleil lamp, 1 

 Siemens lamp, 9 Swan lamps, and 5 other Bernstein 

 lamps placed at a short distance (these lamps re- 

 quired different potentials) ; 2°. At the station of 

 Turin Lango, distant 10 kilometres, 34 Edison 

 lamps of 16-candle power each, 48 of 8-candle power, 

 and 1 Siemens arc-lamp. On the 29th of last Sep- 

 tember the system included the station of Lango, 

 distant 40 kilometres, where 24 Swan lamps, re- 

 quiring 100 volts, were maintained with perfect regu- 

 larity. 



— At Memphis, Tenn., on the Mississippi River, a 

 caving bank rises straight up from the water's edge 

 at its base to a height of from ten to fifty feet. To 

 check the steady disintegration and undermining 

 from the action of the current, the U. S. engineers 

 are employing a method of protection which has 

 been successfully tried at other points on this river. 

 A blanket or willow and pole mattress is placed along 

 the slope of the bank from high-water mark to the 

 bed of the river. These mattresses are some fifty feet 

 wide and from two hundred to a thousand feet long, 

 of flexible willows bound together by poles and wire. 

 They are made on boats having a length equal to the 

 width of the mattress, and are built on an inclined 

 platform, from which they slide down into the water 

 as fast as woven. They are weighted and sunk by 

 stones, and further secured by stakes. The sunken 

 mattresses prevent undermining below the low-water 

 line; and the grading-down of the overhanging bank, 

 by jets of water thrown by powerful steam-pumps, 

 stops all undermining above that line. The space 

 between the upper edge of the mattresses and the top 

 of the bank is protected with willows and stone. 



— In some recent investigations on the growth of 

 leaves, published in the Journal of the society of arts, 

 Messrs. Zoller and Rissmiiller have shown, that while 

 in early summer the leaves of plants contain very 

 considerable amounts of nitrogen, phosphoric acid, 

 and potash, these substances are withdrawn into the 

 wood of the tree with the advancing season; so that 

 before the leaves fade they have lost the larger part 

 of what was most valuable in them, which the tree 

 retains for its future use. In some of these investi- 

 gations on the leaves of the beech-tree, it was shown 

 that in their water-free substance the highest ' per- 

 centage amount' of nitrogen, phosphoric acid, and 

 potash, is found when they open or expand in the 

 month of May, and this percentage quite regularly 

 decreases till they ripen and fall; but the absolute 

 amount of nitrogen, phosphoric acid, and potash, is 

 greatest in July, and from that time on decreases. 



— Mr. I. Millard Reade, C.E., F.G.S., in his presi- 

 dential address to the Liverpool geological society 

 on the denudation of the two Americas, showed that 

 150,000,000 tons of matter in solution are annually 

 poured into the Gulf of Mexico by the Mississippi. 

 This, it was estimated, would reduce the time for 

 the denudation of a foot of land over the whole 

 basin, from a foot in six thousand years to a foot 

 in forty-five hundred years. Similar calculations 

 were applied to the La Plata, the Amazons, and 

 the St. Lawrence, Mr. Reade arriving at the result 

 that an average of a hundred tons per square mile 

 per annum are removed from the whole American 

 continent. This agrees with results he previously 

 arrived at for Europe : the whole drainage into the 

 Atlantic, if reduced to twenty kilometres at two tons 

 to the cubic yard, would equal a cubic mile every six 

 years. 



— The nectar secretion from Aphides is a well- 

 known product. In many cases, however, notably 

 the larch plant-louse, the lice so mimic the twigs on 

 which they rest, that their presence is hard to detect, 

 especially as the lice are often confined to the upper 

 branches of the trees. Often this nectar is secreted 

 so abundantly, that the leaves, and the grass beneath 

 the trees, are covered at early morning by drops so 

 large that it is easy to collect a considerable quantity 

 of the nectar. Sufficient of this nectar can be secured 

 directly from the larch lice and the elm cock's-comb 

 gall lice to test it. Bees are also known to gather it 

 in large quantities. This Aphis nectar is very pleas- 

 ant and wholesome, and unquestionably forms at 

 times no inconsiderable portion of our most beautiful 

 honey. Such honey is light-colored, pleasing to the 

 taste, and perfectly safe as a winter food for bees. 

 The truth of this statement is sustained by the fact 

 that the bees work freely on such nectar, even though 

 the flowers are yielding abundant nectar at the same 

 time. The bees themselves practically proclaim the 

 excellence of this Aphis nectar. 



— The Royal observatory of Brussels has issued the 

 second part of the report upon the transit of Yenus 

 of 1882. Two parties were sent out by the Belgian 

 government, one of which located at San Antonio. 

 Tex. ; the other, at Santiago, Chili. This portion of 

 the report contains a brief narrative of the experi- 

 ences of each party, and the detailed observations 

 which were made. The positions of Venus on the 

 disk were determined solely by micrometric observa- 

 tions, which were successfully made at both stations, 

 though clouds materially interfered with the work at 

 San Antonio. Observations for time, latitude, longi- 

 tude, and meteorological observations, are also given, 

 and a chart is appended containing sketches of the 

 optical phenomena noted at the times of contact. 

 This report forms the second part of volume v. of 

 the 'Annals of the observatory.' 



— In No. 101, in the article by Mr. W. C. Winlock, 

 entitled ' Comets and asteroids of 1884,' the date of 

 the perihelion passage of Wolf's comet should be 

 changed from Sept. 26 to Nov. 17. The name of 

 asteroid (237) is ' Coelestina,' while 'Hypatia' is the 

 name of (238). 



