July 25, 1884.] 



♦ KNOWLEDGE ♦ 



73 



sequent precipitation and resolution of dissolved mineral 

 salts, often to a prodigious degree. In the well-known 

 Dead Sea, in Southern Palestine, one gallon of the water 

 weighs about llijlb., or If lb. more than a gallon of 

 ordinary fresh water. Other lakes, as the salt lakes of 

 Utah and Russia, are almost, if not quite saturated solutions ; 

 whilst still others afford a further stage in being destitute 

 of liquid water ; of this character is the borax lake of Cali- 

 fornia. Doubtles.s the presence of mines of salt in this 

 country, Prussia, and elsewhere, point to former lacustrine 

 deposits which have taken place under analogous opera- 

 tions on the surface of the eaith or in vast underground 

 reservoirs. 



Other lakes are merely expanded portions of rivers, or 

 depressions occasioned by glacial erosion ; and they are 

 commonly provided with both affluent and effluent streams. 

 In such cases the waters are, of course, identical with 

 those of rivers ; their physiographical surroundings, how- 

 evei', make them the recipients ot the first upland drainage, 

 and, as a rule, the water-supjily from such sources is parti- 

 cularly free from impurities. As instances we may point 

 to the waters of classic Loch Katrine, with its " silver 

 .strand " and " Helen's Isle," and of Thirlmere, in Cumber- 

 land ; they contain only about two grains of solid impurity 

 in each gallon. 



5. Hiver Water. — Enough has been stated with regard 

 to the sources of the Thames water to afford a typical 

 example of what may be expected from a river-supply of 

 water. 



6. Underground Waters furnish us with by far the most 

 extensive supply in the world. Wo must once more refer 

 our readers to our foregoing remarks, from which they will 

 gather that rivers and lakes are very largely augmented, 

 and that springs and wells are wholly derived from subter- 

 ranean sources. A species of intestine warfare seems to be 

 perpetually carried on between the pure and impure varie- 

 ties of this element beneath the surface of the earth ; and, 

 on the whole, a kind of equilibrium is established. Surface- 

 waters which become contaminated by their passage through 

 dissolvable soils and rocks, are operated upon by the counter 

 effects of internal heat and other agencies ; they are com- 

 pelled to give up portions of what they have taken, and 

 may thereafter find an escape to the surface of the eaith, 

 from which they originally came, considerably })urified. On 

 the other hand, they may reappear surcharged with the 

 substances they have collected on the way. As a rule, 

 however, the tendency of extensive underground circulation 

 is to render the water purer in the sense of its becoming 

 more valuable to man, and these changes are chiefly brought 

 about through the oxidation or destruction of harmful 

 organic matters, which may accrue from sewage, grave- 

 yards, abundant manuring, decaying vegetation, kc. 



7. Sea Water occupies but a subordinate place in ordi- 

 nary domestic economy. Its saline character is chiefly due 

 to the continued accession of dissolved salts from the 

 earth, which are brought to it by rivers, and which remain 

 behind in the water whilst evaporation is constantly going 

 on from its surface. As a bath, sea-water is often more 

 invigorating than fresh water. In the vessels of the 

 British Navy, and in many recently-built crafts, the waste 

 steam from sea water is utilised by condensation, aerated, 

 and used for drinking and culinary purposes. If a quantity 

 of fresh water be represented by a weight of 1,000 lb., an 

 equal volume of sea water would weigh 1,027 J lb. In 

 consequence of this the boiling point of sea water is much 

 higher than that of fresh water, because an additional 

 amount of heat is necessary to overcome the adhesion 

 between the water and the saline matters. 



(To ie continued.) 



THUNDERSTORMS. 



THIS is a topic to which we shall, when an opportunity 

 presents itself, have occasion to refer with a view to 

 demonstrate that it is possible to guard against such annual 

 calamities as frequently accompany lightning discharges. 



On the three closing days of the week ending July .5 

 thunderstorms of more than ordinary violence passed over 

 England and Scotland, lieports show considerable loss of 

 human life and destruction of property. The storms were 

 accompanied by heavy showers of rain and hail. Some of 

 the hailstones, when ]iicked u|), were found to measure 

 seven-eighths of an inch square, and weigh over two penny- 

 weights. Subjoined i-j a summary compiled by a con- 

 temporary of the effects produced in England and Scotland. 



England. 



Aslon, near WalUnriford. — Two men, while working in a 

 field, were killed. Their clothing was completely con- 

 sumed. A horse in the neighbourhood was also killed. 



Burnley. — Two men were seriously injured. 



Liverpool — At Holy Trinity Church the lightning passed 

 through the roof and through the gallery floor, filling the 

 building with a pale blue flame. The current passed 

 between two boys, paralysing the arm of one and scorching 

 the boot ot the other. The bell was rendered useless, and 

 coping stones were hurled some distance. 



Peterborough. — A number of sheep and cattle killed. 



Weardale. — Wesleyan Chajiel struck, and two men at 

 work on the spire were knocked down insensible, but 

 recovered consciousness afterwards. At Burn Hope a 

 house was partially destroyed. 



Xorthampton. — Lightning struck several dwelling-houses, 

 demolished the turret of a shoe factory, and injured a girl. 



Wymeswood. — Three men, who were at work in the hay- 

 field, took shelter under a hedge. One of the men felt a 

 sharp pain on his thigh, and became insensible. On 

 recovery he found that one of his companions had fallen, 

 while the other was sitting, looking placid and ajiparently 

 undisturbed ; but on examination he found both were 

 dead. 



Skipton. — Tree struck and cut, and a cartload of hay 

 which was being put into a barn set on fire. 



Wimiham. — A stable on the farm of Sir Brook Bridges 

 was struck by lightning and set on fire, three valuable 

 horses being burnt to death. 



Cambridge. — A woman was killed and several buildings 

 were struck by lightning, 



Deddington. — A painter was killed whilst sitting under 

 a tree during a thunderstorm. 



Consett. — Whilst nursing an infant on his knee a miner 

 was struck by lightning and killed, the child escaping. 



Scotland. 



Ilamilton. — The storm, which was at its height about 

 half-past one, continued for fully two hours. About half- 

 past one o'clock, what is described as a ball of fire burst 

 over the Clydesdale Bank, a large three-storey structure in 

 Cadzow-street. The lightning struck the chimney head, 

 racking and displacing the solid stonework, and passing, it 

 is believed, down the chimney. The consternation of the 

 inmates, including the ofiioials of the bank, may be con- 

 ceived. In the room with which the vent communicated, 

 the grate was thrown out on to the floor, and the apart- 

 ment filled with soot, plaster, and debris. Something 

 similar happened in the room on the second floor. The 

 bank otiioe is immediately below on the street floor. The 

 accountant was startled by the noise and falling debris. 



