FRAGMENTS OF SCIENCE. 



863 



test. But mining engineers and pros- 

 pectors are learning that in a mineral- 

 ized region gold may occur in any rock, 

 and hundreds of prospectors are assay- 

 ing all sorts of most unpromising-look- 

 ing rock, satisfied that by assay alone 

 can they determine whether a certain 



rock is gold-bearing or not. This per- 

 sistent and more or less systematic work 

 now going on in every mining district 

 must result in the discovery of many 

 valuable deposits in unexpected locali- 

 ties, and ultimately promises to add 

 largely to the annual output of gold." 



MINOR PARAGRAPHS. 



THE investigations of F. E. L. Beal 

 of the Food of Cuckoos and S. D. Judd 

 of the Food of Shrikes in their relation 

 to agriculture are published in a single 

 bulletin by the Department of Agricul- 

 ture. Mr. Beal finds that the food of 

 cuckoos consists almost wholly of in- 

 sects, of which he has found sixty-five 

 species in their stomachs, and concludes 

 that from an economical point of view 

 they rank among our most useful birds ; 

 and, in view of the caterpillars they eat, 

 it seems hardly possible to overestimate 

 the value of their work. Mr. Judd 

 finds, from a very extensive examina- 

 tion, that the food of butcher birds and 

 loggerhead shrikes consists of inverte- 

 brates (mainly grasshoppers), birds, and 

 mice. During the colder half of the year 

 the butcher bird eats birds and mice to 

 the extent of sixty per cent, and ekes 

 out the rest of its food with insects. 

 In the loggerhead's food, birds and mice 

 amount to only twenty-four per cent. 

 Its beneficial qualities " outweigh four 

 to one its injurious ones. Instead of be- 

 ing persecuted, it should receive protec- 

 tion. 



THE Engineering Magazine is author- 

 ity for the following: " The wrecking of 

 the steamship Paris on the coast of 

 Cornwall and the difficulties encoun- 

 tered in attempting to save her while a 

 number of her compartments forward are 

 filled with water, lead Mr. Richards, in 

 the American Machinist, to suggest the 

 applicability of compressed air. ' There 

 is a means of expelling the water from 

 the filled compartments so obvious, and 

 so certainly effective, that it seems un- 

 accountable that some engineer has not 

 suggested it before this. Close the 

 hatches of the flooded compartments and 

 drive the water out by forcing air in. It 

 would not make the slightest difference 

 how big the holes might be in the bot- 

 tom, as the water would be expelled and 

 kept out on the same principle as in the 



old-fashioned diving bell.' This sugges- 

 tion carries with it a much larger and 

 more important one namely, the use of 

 air pumps instead of water pumps to 

 save a leaking ship while afloat. As Mr. 

 Richards well remarks, the work of try- 

 ing to pump out a leaky ship is not only 

 enormously wasted while it is going on, 

 but it is never finished. If, however, the 

 water leaking into a compartment of a 

 ship be expelled by pumping air into the 

 space, the work is done so soon as the 

 compartment is filled with air down to 

 the level of the leak. After that point 

 is reached the ship is safe, no matter 

 how large the hole, and no further 

 pumping is necessary." 



CHLORATE of potash has always been 

 regarded by manufacturers and chemists 

 as a nonexplosive, and hence there has 

 been little care taken in handling and 

 storing it. A recent explosion, how- 

 ever, at a large chemical works at St. 

 Helens, in England, seems to disprove 

 this view. A storehouse containing 

 about one hundred and fifty tons of 

 chlorate in the form of both powder and 

 crystals took fire, and almost immedi- 

 ately after the falling in of the roof an 

 explosion of terrible violence occurred, 

 the shock being felt over a distance of 

 twenty miles. The chlorate works were 

 entirely demolished. A large gas holder 

 of the city gas works, containing two 

 hundred and fifty thousand cubic feet of 

 gas, was burst and the gas ignited. Eight 

 hundred tons of vitriol was poured into 

 the streets of the town by the wrecking 

 of ten vitriol chambers in a neighboring 

 alkali works. Houses were unroofed, 

 and in the main streets of the town, a 

 quarter of a mile away, nearly every 

 plate-glass window was demolished. A 

 theory accounting for the explosion, ad- 

 vanced by Mr. J. B. C. Kershaw, in the 

 Engineering and Mining Journal, is that 

 it was due to the sudden and practically 

 simultaneous liberation of all the oxy- 



