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THE POPULAR SCIENCE MONTHLY. 



sites of a good sprinkler are that the solder 

 should fuse at a low and well-defined tem- 

 perature, without any appreciable prior soft- 

 ening; that the mechanism should not be 

 liable to get out of order or stick ; that the 

 parts opened by heat should be capable of 

 ready replacement without skilled labor; 

 that there should be no leakage at the 

 valve ; and that the quantity of solder to be 

 melted should be small, and so placed that 

 it is not cooled by contact with too great a 

 mass of metal, or exposed to the drip of the 

 opening valve. Closely allied to the auto- 

 matic sprinkler proper is the system of 

 sprinkling by perforated pipes through an 

 automatic valve. The automatic fire-door, 

 which should not be of iron, because it curls 

 up, but of wood protected by sheathings of 

 tin-plate, is arranged to shut on an inclined 

 track, and is kept open by a rod made with 

 a scarf -joint in two parts twisted in the 

 center, and secured by a fusible solder ; or 

 the door may be held by a cord holding a 

 weight, the fall of which releases the door ; 

 the fall to be produced by the melting of a 

 solder set in some convenient part of the 

 cord. Another class of devices depends 

 upon the introduction into the electric cir- 

 cuit of a fusible link, the melting of which 

 breaks the circuit ; or into the broken cir- 

 cuit of a strained catgut band, the contrac- 

 tion of which by the heat brings the wires 

 into contact. In one of the applications of 

 this system a reservoir of carbonic acid is 

 opened and the acid distributed. Mr. John 

 has invented an arrangement for making the 

 hand grenade extinguisher automatic. He 

 proposes to hang the grenade at the top of 

 a room in a sort of a cage, which is pro- 

 vided with a small button held together with 

 fusible alloy. When that is affected by the 

 ascending hot air, the button bursts, and the 

 cage opens and allows the grenade to fall, 

 while an iron weight follows it, and, break- 

 ing it in mid-air, causes the liquid to be 

 sprinkled about. 



Parasitic Fungi on Plants. Professor 

 T. J. Burrill, in a paper of the Illinois State 

 Laboratory of Natural History on the para- 

 sitic fungi of the State, remarks with ref- 

 erence to the nature of these pests, that 

 " during the last part of the first half of 

 this century learned discussions arose upon 



the specific distinction between the parasite 

 and the host, and esteemed botanists held 

 the view that what was taken for the for- 

 mer was but a diseased condition of the lat- 

 ter the rust of wheat, for example, was 

 only the degraded cell-tissues of the wheat 

 itself. Such difference of opinion, however, 

 no longer exists among those who have pos- 

 session of the information now acquired. 

 The tissues of higher plants do not change 

 by any process of degradation or transfor- 

 mation into the things called fungi, neither 

 do the latter originate in any other manner 

 than as descendants of pre-existing forms 

 through as rigid specific lines as can be 

 traced among any animals or plants. It is 

 known, too, that however much the fungus 

 is found within the tissues of the host-plant, 

 it began its growth outside of the latter, 

 and gained introduction only by forcible en- 

 trance. Spores are never taken up by ab- 

 sorption and carried by the aqueous cur- 

 rents from part to part of the plant. The 

 fungus passes through the tissues very much 

 as roots pass through soil, sometimes appar- 

 ently without in any degree successful op- 

 position, sometimes nearly or quite baffled 

 in the struggle by the mechanical and physio- 

 logical resistances of the host-plant." 



The Punjab. The Punjab derives its 

 name which means " five waters " from 

 the five great rivers traversing it the Jhe- 

 lum, Chenab, Ravi, Beas, and Sutlej which, 

 united, flow into the Indus about five hun- 

 dred miles above its mouth. In early times 

 the country was called the land of the 

 " seven rivers," and the Indus itself, on the 

 one side, and the Saraswati, on the other 

 side, were counted in addition to the five 

 streams already named. The Saraswati, 

 according to General R. Maclagan, presents 

 an interesting problem. All the other rivers 

 of the seven take their rise in the snows of 

 lofty mountains, and, being fed from unfail- 

 ing sources, are always great streams ; but 

 the Saraswati rises in the low outer hills, 

 depends on periodical rains only, and, while 

 subject to floods, is dry for a great part of 

 the vear. Even in the flood season, the 

 water with which its upper valley is inun- 

 dated runs off so quickly that it all disap- 

 pears before it can reach the Sutlej or the 

 Indus. Yet in the ancient Indian writings 



