516 Scientific Intelligence. 



region of great A of the second order, which possess all the 

 detail and definition usually so characteristic of the violet end. — 

 Nature, April 2, 1891, p. 525. j. t. 



10. Lecture exjieriment on magnetic screening of conducting 

 media. — J. J. Boeg^iax describes the following experiment. A 

 Lecher's tube (Ann. der Physik und Chemie, xli, p. 850) is put 

 by means of two cork rings into another large (4 cm. diam.) glass 

 tube, with a crane on one end. Holding the tube in one hand, 

 and approaching it to a wire in which electrical waves are pro- 

 duced, a continuous lighting of the tube is seen. If the outer 

 tube is filled with dilute sulphuric acid the light disappears. 

 This is not the case when the outer tube is filled with water. — 

 Nature, April 23, 1891. j. t. 



II. Geology axd Xatural Histoey. 



1. Eruption of Kilo.uea. — The Daily Pacific Commercial Ad- 

 vertiser of April 30th reports the following additional facts : "The 

 breakdown is slightly larger than the one of 1886. It also differs 

 from the one of 1886 in the following respects : in 1886 the fire 

 appeared to have entirely gone out, there seemed to be little 

 steam left, and for three months the crater was absolutely dead 

 and cold, with the exception of the still warm lava which had run 

 out prior to the breakdown. The lava then came back slowly, 

 and it was considerably over a year before the whole basin filled 

 up again. The breakdown of 1891 left hot lava still to be seen 

 in the cracks around the edge of the breakdown, and dense 

 clouds of vapors, steam and intense heat arising at several points 

 from the bank. After a lapse of only three weeks the molten 

 lava again appeared in the pit, and it is now filling up rapidly. 

 The news brought by the steamer W. G-. Hall was that up to the 

 26th inst. the bottom«of the pit had filled up about 100 feet, and 

 a lake of liquid lava formed some 250 to 300 feet in diameter. 

 This is the result of only ten days' action. The bottom of the 

 pit was steadily rising and the size of the lake increasing, and 

 activity showing itsell at new points every day. The illumina- 

 tion was very bright, being visible at night at Punaluu, thirty 

 miles away." 



2. Geological Survey of Ohio. — First Annual Report under 

 the third organization by Edward Orton, State Geologist. 330 

 pp. 8vo. — This very valuable report, chiefly by Professor Orton, 

 treats of the origin and accumulation of mineral oil and natural 

 gas, and of the Trenton and Clinton limestone and other rocks in 

 Ohio, as sources of these materials. The chapters on these topics 

 are preceded by one on the general geological structure of Ohio. 

 The report is accompanied by two maps of the oil fields and gas 

 fields. It closes with a chapter on the measurement of natural 

 gas in gas wells, pipe lines, etc., by S. W. Robinson. 



3. Iron Ores of Minnesota by N. H. Winchell and H. V. 

 Wixchell. Bulletin- Xo. 6 of the Geological Survey of Minne- 

 sota, 420 pp. 8vo. With a geological map, 44 plates and 26 



