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THE POPULAR SCIENCE MONTHLY, 



tice. Mr. rieuss has also, in conjunction 

 with Mr. Foster, produced a safety mining- 

 lamp which depends for its vitality on prin- 

 ciples similar to those of the breathing ap- 

 paratus, and is equally useful and safe un- 

 der water and in the most dangerous gases. 

 It is essentially a lime-light, ignited by the 

 burning of methylated spirits instead of 

 hydrogen gas, and securely guarded against 

 contact with the outer air. It will burn for 

 four hours equally well under water, in car- 

 bonic acid, or in fire-damp, and it can not 

 get hotter than boiling water. Its useful- 

 ness, says " Iron," " we have seen demon- 

 strated by a diver at the Fisheries Exhibi- 

 tion, who, equipped with the breathing ap- 

 paratus, and having a Fleuss lamp, remained 

 for long periods under water, both man and 

 lamp being wholly cut off from the outer 

 atmosphere during the periods of immer- 

 sion. In like manner we have seen the re- 

 spiratory apparatus put to the test by a man 

 equipped with it remaining for some time 

 in an air-tight iron chamber filled with 

 dense smoke and noxious vapors. But 

 above and beyond this is the experience 

 which has been gained from its use in 

 actual practice, notably in the case of the 

 flooding of the Severn Tunnel, as regards 

 subaqueous work, and in the cases of the 

 Seahara and Killingworth collieries with re- 

 spect to coal-mine accidents." In the case 

 of the explosion at the Lycet collieries, in 

 which several lives were lost, an early ex- 

 ploration, which in ordinary circumstances 

 would have been impossible, was safely 

 effected by means of the Fleuss apparatus. 



The Army-Worm. — Several caterpillars 

 have been popularly but inaccurately called 

 the army-worm ; but, according to the re- 

 cently published pamphlet by Professor Ri- 

 ley on the subject, the real worm which is 

 so destructive to growing grass and grain is 

 the Leucania nnipunctata, a species that 

 has a very wide range on this Continent. 

 The worm is the larva of a moth about an 

 inch and a half in wing-expansion, and of a 

 reddish-gray color, which lays its eggs in 

 wild or cultivated grass, or in grain, along 

 the inner base of the terminal blades, where 

 they are yet doubled, or between the stalk 

 and its surrounding sheath, or even in the 

 cut straw of old stacks, or in corn-stalks. 



The larvge feed for a time after hatching in 

 the fold of the leaf, which they so resemble 

 in color as usually to escape observation. 

 They are stationary in habit so long as they 

 have sufficient feed, but take up the march 

 when their pasture is exhausted ; and in those 

 seasons when they have been multiplied to 

 excess they constitute a veritable army 

 marching in solid rank. Their occasional 

 sudden appearance in vast numbers over 

 large stretches of territory is one of the 

 phenomenal features of their life; but it 

 is not so wonderful a fact, after all. They 

 are nearly always with us in greater or less 

 numbers, and if the season is a dry one they 

 multiply prodigiously. An immense crop 

 of moths is accordingly produced, and then, 

 each one of them laying seven or eight hun- 

 dred eggs, stock the fields and pastures in 

 profusion, depositing the eggs for the im- 

 mense host which is to appear in the follow- 

 ing year. In confirmation of this view, ex- 

 aminations of the weather records show that 

 the years preceding army-worm years have 

 been universally characterized by drought. 

 Three broods of them may be produced in 

 a year. Their natural enemies are not less 

 than fourteen species of birds, a metapo- 

 dious bug, and numerous parasites. The 

 usually applied remedies look to the whole- 

 sale destruction of the worms or the eggs. 

 Among them are burning the old grass, pref- 

 erably as late as possible in the spring ; 

 digging a ditch to serve as a trap into which 

 they will fall on their march, after which 

 they may be destroyed in various ways — 

 mashing them in the field with heavy rollers, 

 and dragging a rope across the field to crush 

 them. Thin tillage is also a preventive, by 

 causing the worms to be exposed to the sun. 



What destroyed Casamicciola ? — Pro- 

 fessor Palmieri, of the Mount Vesuvius 

 Observatory, believes that the destruction 

 of Casamicciola, in Ischia, was not the im- 

 mediate effect of the earthquake, but was 

 caused by a caving in of the ground under 

 the city, which might, perhaps, have been 

 precipitated by an earthquake-shock. The 

 trachytic rocks on which the town is built 

 rest upon a bed of clay, in which extensive 

 galleries have been dug in the course of 

 centuries, while the clay has been mined 

 for industrial purposes. As early as 1837, 



