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THE POPULAR SCIENCE MONTHLY. 



nodules and zeolitic crystals. It has not 

 yet been possible to recognize the analogues 

 of the deposits now forming in the abysmal 

 regions in the rocks making up the conti- 

 nents, but it is quite otherwise in the areas 

 bordering on the continents. Almost all 

 the matter brought down to the ocean in 

 suspension is deposited in this region, which 

 is that of variety and change, with respect 

 to light, temperature, motion, and biological 

 conditions. It extends from the sea-shore 

 down, it may be, to a depth of three or four 

 miles, and outward horizontally from sixty 

 to three hundred miles, and includes all 

 partially inclosed seas. Plants and animals 

 flourish luxuriantly near the shore, and ani- 

 mals extend in relatively great abundance 

 down to the lower limits of the region. 

 Ilere we find now in process of formation 

 deposits which will form rocks similar to 

 those making up the great bulk of con- 

 tinental land. Throughout all geological 

 time the deposits formed in this border or 

 transitional area appear to have been pushed, 

 forced, and folded up into dry land, through 

 the secular cooling of the earth and the ne- 

 cessity of the outer crust to accommodate 

 itself to the shrinking solid nucleus within. 

 The changes in the abysmal region, though 

 great, are not comparable with these. The 

 results of many lines of investigation seem 

 to show that in the abysmal regions we 

 have the most permanent areas of the 

 earth's surface. 



Rivers underground. General R. Mac- 

 lagan, describing the rivers of the Punjab 

 before the Royal Geographical Society, re- 

 marks that, when the measure is taken of 

 the water in a river flowing in a wide chan- 

 nel in soft soil, we do not at any time get the 

 whole of it. We measure what is flowing 

 above the bed, but there is more beneath. 

 It sinks down till retained by some imper- 

 vious stratum, and may become something 

 like a second river flowing under the larger 

 one which we see. It happens sometimes 

 that the whole of a small stream sinks into 

 porous soil and disappears, and, if a reten- 

 tive stratum which it meets beneath comes 

 out to the surface at a lower part of its 

 course, the filtered water will pour out and 

 become a surface river again, after the or- 

 dinary manner of streams. The experiment 



has been made on the Jumna of shutting off 

 the whole visible river with a weir and turn- 

 ing it into the canals on either bank. A few 

 miles below, the water trickles down into 

 the bed again, and farther below there is a 

 river as before. In most river-beds, like 

 those of the Punjab, when they are left dry 

 at the sides in the low season, water is to 

 be got under the dry bed, as well as under 

 the river, and usually at no great depth. 

 Plenty of water can often be got by scoop- 

 ing a mere hole. The water-supply of La- 

 hore is pumped from wells sunk in the bed 

 of the Ravi. The water which sinks under 

 the beds of these great rivers finds a wide 

 field of hidden usefulness open to it when 

 it gets beneath. Spreading abroad it meets, 

 and helps to make, the great underground 

 lakes and springs on which every country 

 so largely depends. In the rainless tract 

 around the meeting of the rivers in the 

 south of the Punjab, this underground re- 

 serve of water is abundant and near the 

 surface. In the distribution of the reserves 

 there are great variations, according to the 

 varying extent, form, and positions of the 

 dividing walls of impermeable soil. The 

 admission of water to new canals is com- 

 monly followed by the rise of the water- 

 level in wells within a certain distance on 

 either side. Like the Mississippi, the Indus 

 has in a part of its course raised its bed by 

 the deposition of silt, so that for nearly four 

 hundred miles it runs on an embankment 

 made by itself, with long gentle slopes on 

 both sides down to the general low level of 

 the country. As along the Mississippi, the 

 country is protected by dikes, and danger is 

 apprehended in flood-times from crevasses. 



Advantages of Sea-Voyages. A medical 

 writer in " Chambers's Journal " makes a 

 warm recommendation of sea-voyages as a 

 means of restoring health and strength. 

 Among the chief advantages of a voyage 

 are the perfect rest and quiet it secures. It 

 is sure to take the passenger and keep him 

 for a time out of the reach of all home an- 

 noyances and home drudgeries, and in many 

 cases out of mind of them. He " has only 

 to eat, sleep, and live. The strain of life is 

 withdrawn. The wheels of existence move 

 easily and with lessened friction. The in- 

 cessant emulation, the keen anxieties, the 



