September 19, 1895] 



NATURE 



D' j 



the city of Berlin alone consumes daily with its milk 300 cwt. of 

 cow dung ! 



Although the extension of geological research into distant 

 parts of the earth has shown that the divisions of time originally 

 made in Europe are not always applicable to other areas, yet it 

 is possible that the greatest geological division-lines that are 

 recognised may represent world-wide periods of rapid change. 

 Such is the view expressed by Prof. Le Conte in a paper on 

 "Critical Periods in the History of the Earth," published by 

 the University of California. He considers that in the evolution 

 of the earth there must have been now and again, amid many 

 smaller local changes, readjustments of the crust affecting the 

 whole earth, with something approaching simultaneity. Such 

 universal changes must be used to mark out the primary 

 divisions- of time : they are marked by widespread unconfor- 

 mities and the birth of great mountain-ranges, and as conse- 

 quences of these changes in physical geology there follow 

 remingling of faunas, the extinction of many types, the more 

 rapid evolution of new forms, and the origin of new dominant 

 classes. We thus have an alternation of short " critical " 

 periods of extensive change and long periods of gradual change, 

 the former marking the commencement of the great time- 

 di\-isions of che earth's history. Four such critical periods can, 

 in Prof. Le Conte's opinion, be recognised — the pre-Cambrian, 

 the post-PaljEozoic, the post-Cretaceous, and the Glacial. Com- 

 paring these with one another, he finds progressive change in 

 their character ; each one is shorter in duration than the previous 

 one, and involves greater climatic changes and increased faunal 

 effects from the introduction of new dominant types. 



Dr. Gerhard SrHOTT has published some interesting maps 

 concerning the present conditions of sail navigation, which are 

 appended to his paper on the subject appearing in the Zeitschrift 

 der Gesellschaft fiir Erdkunde. They are chiefly compiled from 

 log-books examined at the Deutsche Seewarte, Hamburg. The 

 two main lines of voyages for German .sailors are the " saltpetre 

 trips " to the west coast of South America, and the " rice trips "' 

 to India and the Straits Settlements. A map divided into zones 

 of equal travelling times from the Lizard shows the remarkable 

 fact that the mouth of the Congo is one of the most difficult 

 parts to reach in a sailing vessel. The Cape and Patagonia can 

 be reached in the same time. The southern Indian Ocean 

 forms a kind of racecourse along which the vessels speed to 

 Australia in the .same time as it would take to reach Zanzibar. 

 Adelaide can be reached in ninety days, and so can Chile. New 

 ^'ork, which requires forty days, is in that respect as distant as 

 Panama, and is one of the most inaccessible ports for a sailing 

 vessel, especially in the winter. The return is easier, and can 

 be accomplished in twenty-five days, whereas the return from 

 Panama takes sixty. The return from .Australia is equally 

 lengthy round the Cape as by Cape Horn, and the latter route 

 is now preferred owing to the notoriously dangerous character of 

 Cape .\gulhas. Needless to say, the Suez Canal is quite useless 

 for sailing vessels. Even apart from the fact that the Red Sea 

 is most difficult to navigate, the canal dues exclude vessels 

 whose vitality lies solely in the cheap freights they can offer in 

 competition with steamers. With the modern construction of 

 sailing vessels, which are built almost exclusively of iron and 

 steel, the only enemies seriously feared are fogs, icebergs, and 

 dead calms, to which we must add, in the much-frequented ocean 

 highways of the northern Atlantic, the fast mail steamer. The 

 average skipper does not mind a storm, but rather welcomes it, 

 as it makes him go all the faster. 



The fouriial of t/w Frank/in Insliliitc states that the recent 

 trials of electric locomotives at Nantasket Beach, near Boston, 

 and at Baltimore, have so satisfactorily demonstrated the 

 superiority of this class of motor over the steam locomotive for 



NO. 1351, VOL. 52] 



short hauls, that it is now ver)' generally admitted that the near 

 future will witness a very extensive application of the new form 

 of motive power for short branch lines, tunnel haulage, &c. At 

 the Nantasket Beach trials, it is stated that a speed exceeding 

 sixty miles an hour was attained, and at Baltimore the test of 

 the electric locomotive designed to draw trains through the 

 tunnel, 7430 feet long, in that city, was highly successful. A 

 maximum speed of fifty miles an hour is to be developed, and 

 it is guaranteed that the locomotive will pull 1 200 tons at a speed 

 of thirty miles an hour. The system has been in practical and 

 regular operation on the Nantasket Beach Railway since the end 

 of June last. 



AccORDiNc; to the Engineer, a French physicist, M. Denay- 

 rouze claims to have discovered a means of increasing the illum- 

 inating power of gas about fifteen times. In his lamp M. 

 Denayrouze employs a spherical-shaped metallic body, and a 

 mantle capable of being raised to incandescence. In the body 

 of the lamp is fixed a tiny motor, which works a ventilator, and 

 which receives current from a couple of small accumulators. 

 The electrical energy required is said to be only J volt and iV, of 

 an ampere, and to be sufficient to force a current of air through 

 the mantle and to cause the gas to bum with remarkable 

 brilliancy. The burner is said to consume seven litres of gas 

 per carcel, and lamps have been made having an illuminating 

 jjower of 8oo-candle power. 



Speaking of some experiments in marching, which have 

 recently been carried out at the request of the German War 

 Office, by some students of medicine of the Friedrich Wilhelm 

 Institute in Berlin, who for the purpose wore the regulation 

 uniforms and carried the full field service equipments, the FIritish 

 Medkal loiirnal ?ays: — "The marches performed varied from 

 22 to 33 miles, and were executed in all kinds of weather. The 

 weights or loads carried varied from 48 to 68 lbs., the full ser- 

 vice equipment of the German infantr)' soldier averaging 70 lbs. 

 That of our own infantry does not usually exceed 60 lbs. The 

 conclusions arrived at by the medical officers in charge of the 

 experimental observations were practically as follows : When 

 the load is not excessive and does not exceed 48 lbs. a march of 

 twenty-five miles executed in cool weather (60' F.) is readily 

 performed, and has no deleterious effects upon the man, even if 

 continued for some days consecutively. With a mean tempera- 

 ture of 70° F. a similar load carried the same distance has a 

 considerable temporary effect upon the organism, necessitating a 

 rest of at least ten hours in the twenty-four. A load of 68 lbs. 

 could not be carried twenty-five miles without inducing grave 

 physiological disturbance, necessitating a full day's rest on the 

 following day. This weight was not readily carried day by day 

 without derangement of health over greater distance than fifteen 

 miles. A weight of 60 lbs. was the maximum weight which 

 could be carried on consecutive days for twenty-five miles by a 

 man weighing 1 1 stone during ordinary summer weather con- 

 sistently with health. It is not stated whether the men by whom 

 these experiments were made were picked individuals, or what 

 was their dietary." 



The current number of The Leisure Hour contains an 

 interesting article by E. WTiymper, on some high mountain 

 observatories, accompanied by illustrations and short accounts 

 of the difficulties experienced and the results attained. The 

 observatories described are : — Mount Washington, in New 

 Hampshire, U.S.A., 6286 feet high ; it was established in 1870, 

 but is now closed. Pike's Peak, in Colorado, 14,134 feet high, 

 wiis erected in 1873, and closed in 1888. This station was 

 celebrated for its electrical storms. The most elevated station is 

 on the top of the Misti, near .-Vrequipa, in Peru. This is 19,200 

 feet above the sea, but notwithstanding its great elevation, the 

 ascent is comparatively easy. About twelve miles to the north 



