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THE POPULAR SCIENCE MONTHLY 



plummet, has reached the required depth, 

 an electric current is sent from the battery 

 on shipboard to the coils below ; the mag- 

 netism thus generated opens the valves, 

 and the vessel is filled and ready to be 

 drawn up. 



In his evidence before the Royal Com- 

 mission on the water-supply of London, Dr. 

 Parkes states that where the population of 

 any town shows a considerable amount of 

 diarrhoea, and also of typhoid fever, it 

 would lead him to regard the water-supply 

 with suspicion ; for the health of the popu- 

 lation, as regards these diseases of the intes- 

 tines, seems to be very much influenced by 

 the purity or impurity of the water con- 

 sumed. 



It is proposed to employ tin-foil in place 

 of paper for decorating walls. The foil for 

 this purpose is cut in sheets about 16 feet 

 long and 40 inches wide. After having 

 been painted and dried at a high tempera- 

 ture, the sheets receive the ornamental fig- 

 ures, and are then varnished and again 

 dried. The hanging is done much like 

 paper-hanging, varnish being applied to the 

 wall instead of paste. The foil excludes 

 damp, and can be laid as readily on an ir- 

 regular as on an even surface, and thus 

 the highest artistic effects can be produced 

 at pleasure. 



A writer in Hardwicke's Science Gossip 

 tells of a water-wagtail which he saw act- 

 ing as purveyor to a young cuckoo. The 

 wagtail was seen, again and again, to fly 

 down from a tree, and run along the rail on 

 which the cuckoo was perched, bringing 

 each time to the latter some insect to sup- 

 ply its hunger. 



Orange Cultivation in Louisiana. 

 There is a steady increase, in the orange 

 district of Louisiana, of this species of hus- 

 bandry. In Plaquemine Parish some 2,000 

 acres are occupied by orange-groves. Usu- 

 ally, there are one hundred trees to the 

 acre, and a healthy tree will bear from 500 

 to 2,000 oranges, 1,000 being a fair average 

 field. They bring, on an average, $10 per 

 thousand. 



The iron mountains of Missouri, accord- 

 ing to Prof. Waterhouse, contain enough 

 ore above the surface, to afford, for 200 

 years, an annual supply of 1,000,000 tons. 

 Shepherd Mountain is 600 feet high, and 

 its ore contains a large percentage of 

 iron. Pilot Knob rises 1,114 feet above 

 the Mississippi; its base, 581 feet from 

 the summit, is 300 acres, and the upper 

 section of 141 feet i3 judged to contain 

 14,000,000 tons of ore. Iron Mountain has 

 an elevation of 228 feet, and an area of 

 500 acres at its base. The soild contents 

 of the cone are 230,000,000 tons. At the 



depth of 150 feet, the artesian auger was 

 still penetrating solid ore. The iron from 

 all these mountains is strong, tough, and 

 fibrous. 



Dieh, October 28th, aged sixty-five, Dr. 

 Friedrich Welwitsche, the distinguished 

 African botanist. He got his first lesson in 

 his favorite science from a village apothe- 

 cary, and so an interest was awakened for 

 botanical studies. The " Flora of Tropical 

 Africa " has received from him very im- 

 portant contributions. He acquired distin- 

 guished reputation also as an entomologist 

 and zoologist. 



In criticising the evidence given by Dr. 

 Letheby before the Royal Commission on 

 the London water-supply, Dr. Hassel, in 

 " Food, Water, and Air," maintains that " it 

 is a fact, notwithstanding Dr. Letheby's 

 evidence, well-established and generally ac- 

 cepted, that cholera is communicable by 

 water, and has, over and over again, been 

 disseminated by the water contaminated by 

 cholera-discharges. It is also a fact that 

 on more than one occasion that dreadful 

 disease has been communicated by Thames- 

 water." 



A recent issue of French coin, made 

 from Australian gold, has been found so 

 brittle as to break easily under ordinary 

 use ; it has accordingly been recalled. The 

 brittleness is supposed to be due to the 

 presence of a small percentage of antimony 

 and arsenic, both extremely difficult to re- 

 move. These substances are said to pro- 

 duce a like effect in all metals or alloys 

 which are subjected to the molecular changes 

 induced by the pressure and heat devel- 

 oped under the action of the dies in the 

 copying-press. 



The -archives of the Paris Jardin des 

 Plantes contain 6,000 volumes and over 

 1,500 manuscripts that have hitherto been 

 huddled away as so much lumber. Recent- 

 ly M. Milne-Edwards has arranged for ex- 

 amining, cataloguing, and placing at the dis- 

 position of the scientific world this valuable 

 collection. There are several MS. by Buf- 

 fon, Cuvier, and Daubenton, and a series of 

 pen-and-ink drawings by the last-named 

 naturalist, representing the various types 

 of merinoes ; also many albums filled with 

 drawings of plants and flowers. 



Dr. Gunther shows that the whitebait, 

 a fish highly esteemed by epicures, is noth- 

 ing but the fry or young of the herring, and 

 this he proves by showing that both fish 

 have the same number of vertebrae and of 

 lateral scales, as also the same arrangement 

 of fins and teeth. This statement is fur- 

 ther confirmed by the fact that an adult 

 whitebait in roe has never been found. 



