POPULAR MISCELLANY. 



57* 



sary. The best nurses are the calmest nurses, 

 and they are very seldom the ones who suf- 

 fer most at the sight of their patients' suffer- 

 ing ; and " one of the great advantages which 

 patients feel on entering a hospital is that 

 their sufferings do not come back reflected 

 from the faces of those around them ; that 

 the sympathy they excite is only a mild 

 sympathy, and not one which heightens their 

 own pain. . . . Hardly a sufferer exists who 

 is not the better instead of the worse for 

 seeing that those around him are not over- 

 whelmed by his sufferings — that, so far as 

 he can go out of himself at all, he may get 

 a little relief by entering into the less over- 

 shadowed lines around him, and tasting in- 

 directly another's enjoyments." 



A Theory of Volcanic Action. — Mr. J. 



Logan Lobley explained in the British As- 

 sociation last year a theory of the causes of 

 volcanic action which he had reached while 

 keeping in view forty-two leading and con- 

 trolling facts. His conclusions are, that the 

 primary cause of the formation of lava is 

 the internal heat of the globe inducing chem- 

 ical action in subterranean regions when the 

 materials and conditions are both favorable ; 

 that since the fusion-point of solids is raised 

 by extreme pressure, the conditions for chem- 

 ical action may be changed by the removal 

 of vertical pressure or its relief by lateral or 

 tangential pressure ; that certain substances 

 are fusible at low or moderate temperatures, 

 and that thus at very moderate depths chem- 

 ical action may be locally commenced that 

 will extend until sufficient heat is produced 

 to effect rock-fusion ; that the cause of the 

 ejection of lava from its source, and of its 

 rise in the volcanic tube, is the increase of 

 bulk consequent upon the change from the 

 solid to the fluid state, aided by the forma- 

 tion of potentially gaseous compounds by 

 chemical reactions among the original mate- 

 rials of the magma ; that the ascent of the 

 lava in the volcanic tube may be affected by 

 the weight of the atmosphere and by lunar 

 attractive influence ; that the explosive effects 

 of volcanic eruptions are altogether second- 

 ary, and are due to the access of sea and 

 land water to fissures, by percolation through 

 cool rocks, up which lava is ascending ; that 

 this water, when converted into steam, opens, 

 by its expansive power, rents that admit 



large flows of sea-water to the lava, occasion- 

 ing the formation of vents and the greater 

 explosive phenomena of eruptions. The for- 

 mation of the actual surface volcano and 

 the determination of its position are there- 

 fore due to the sea, near which volcanoes 

 are almost always situated. Emissions of 

 lava without explosive effects are from vol- 

 canic tubes to which large flows of water 

 have not obtained admittance ; and, on the 

 other hand, purely explosive eruptions, with- 

 out lava-flows, are caused by water reaching 

 lava which fails to rise to the surface of the 

 earth. 



Fire-proof Honses in Buenos Ayres. — 



They build fire-proof houses in Buenos Ayres 

 and Montevideo without thinking of it, and 

 while using all the wood they can afford to ; 

 and they use neither iron nor the arch. Trees 

 are scarce in the neighborhood, and timber 

 has to be brought down from the upper 

 waters in hard woods. Being dear, a little 

 of it is made to go as far as possible. The 

 floors and the roofs are supported by joists 

 of hard wood, as among us ; across these are 

 laid flat rails of the same, and the spaces 

 between these are bridged over by thin 

 bricks thirteen inches and a half long, with 

 their ends resting on the rails ; another layer 

 of bricks is then laid with lime, and gener- 

 ally on this a layer of flat tiles. The doors 

 and windows have no boxes, but simply 

 frames, which are set up when the walls are 

 going up, and built in. There is no lathing, 

 or wainscot, or skirting of the bottom of the 

 walls. A house thus built can not be burned. 



Glass-Blowing by Machinery. — A system 

 for glass-blowing by machinery, under which 

 mouth-blowing is dispensed with, has been 

 devised by Mr. Howard M. Ashley. In the 

 machine, the molten metal is delivered into 

 a receptacle called a parison, which holds 

 just enough metal to form a bottle. At the 

 bottom of the receptacle is a collar mold, 

 which forms the ring around the mouth. 

 The central portion of the mold — which may 

 be described as a punch within a punch, 

 from the method in which it works up into 

 the molten glass to make the collar — is hol- 

 low, and is connected with a reservoir of 

 compressed air. After the collar is molded, 

 the mold is turned upside down, a little air 



