230 



NA TURE 



[January 9, 1902 



E. F. Nichols and G. 1'". Hull, which was read at a joint meeting 

 of the American Physical Society and the American Association 

 for the Advancement of Science on August 29, 1901, and is 

 published in the Physical A'eview for November last. The 

 experimental methods adopted by Messrs. Nichols and Hull are 

 similar to those employed by Lebedew, the chief difference 

 being that whereas the former used a bolometer to measure the 

 incident energy the latter employed a calorimeter, but the 

 investigation is not as yet of so complete a nature. The obser- 

 vations already completed are, according to the authors, 

 sufficient to prove experimentally the existence of a pressure of 

 the nature and order of m.ignilude of radiation pressure. The 

 results agree to within about 30 per cent, with the theoretical 

 value : a certain amount of inexactness is introduced as the 

 authors did not experimentally determine the reflecting power of 

 the vanes employed. Lebedew in his investigation claims to 

 have obtained results agreeing to within 10 per cent, with the 

 calculated values of the Maxwell-Bartoli pressure. 



In view of the trials now being made by one of the London 

 water companies with ozonised air as an agent for water purifi- 

 cation, the following details of the experimental plant erected 

 by Siemens and Halske at Martinikenfelde, near Berlin, are of 

 interest. This plant was erected in 1S9S, and is adapted for 

 treating 240 cubic metres water per twenty-four hours. The 

 ozonisers are of the Siemens and Halske plate and tube type, 

 and yield 20-25 grams ozone per E.H.P. hour, with an E.M.F. 

 of 12,000 volts. The air passing from the ozonisers under 

 these conditions contains 2^-3 grams ozone per cubic metre. 

 An air-pump is used to force the air through the drying chamber 

 into the ozonisers, and it passes thence into the sterilising 

 tower. This tower is a simple square structure packed with 

 flints, and as the ozonised air passes upwards it comes into 

 contact with a descending stream of water. The remainder of 

 the plant at Martinikenfelde consists of a water-pump, a sand 

 filter for preliminary filtration of the water with which the 

 sterilising tower is fed, and various storage tanks for the filtered 

 and unfiltered water. Tests made with water from the River 

 Spree show that the numbers of bacteriological organisms were 

 reduced from 600,000 to 10 per cubic centimetre. The per- 

 manganate absorption figure was reduced 18 per cent., and the 

 aeration of the water was increased from 10 per cent, to 12 

 per cent. The consumption of ozone amounted to two grams 

 per cubic metre. The cost of treatment for an installation 

 treating 120-150 cubic metres per hour was estimated to be 

 1726 pfg. per cubic metre, and the total cost, when interest 

 and depreciation charges on the distributing system are in- 

 cluded, 5'03i pfg. per cubic metre (equal to \s. $if. per 1000 

 cubic feet). The capital outlay upon an installation capable of 

 treating 150 cubic metres per hour was estimated to be 6750/., 

 of which total 3750/. represented the expenditure upon the 

 ozonisers and sterilising tower. Further details will be found in 

 an article by Dr. Erlwein in the Zcitschrift fiir Electro- 

 citemie, November 14, 1901. 



Mr. Se.\le, in Occasional Papers (vol. i. No. 4) of the 

 Bernice Pauahi Bishop Museum, Honolulu, describes and figures 

 several new Hawaiian marine fishes. 



In the Cotnptes reitdus of the Swiss Society of Natural 

 Science for 1900 Dr. Katio adds two vertebrate.s — the lesser 

 shrew {Sorex pyginaeus) and the Grecian frog (Rana gracca) — to 

 the fauna of Switzerland. 



In an article published in the licvue Scientifiqiie (Revue Rose) 

 of December 28, 1901, M. Hugo de Vries discusses the mutations 

 of species and the periods required for such mutations. He 

 mentions that since certain plants have apparently remained 

 unaltered since the date of the building of the pyramids 

 NO. 1680, VOL. 65] 



(approximately 4000 years), this period may be taken as a 

 minimum unit in estimating the time required for specific 

 modification. 



To the eighty-third volume of the Verhandltingen of the 

 Swiss Naturalists' Society Prof. C. Keller communicates a very 

 interesting dissertation on a peculiar breed of domesticated 

 sheep with goat-like horns formerly kept by the natives of the 

 Biinden Oberland, Switzerland, and hence locally known as 

 the Biindnersch. The breed is known to be of great 

 antiquity, but now appears to be almost exterminated owing 

 to crossing with other strains. In 1S62 the late Prof. 

 L. Riitimeyer called attention to the peculiarity of this breed, 

 and indicated its near affinity with the so-called peat-sheep 

 (Torfschaf) of the Swiss lake-dwellings, of which it appears to 

 be the direct descendant. The author expresses the hope that 

 efforts may be made to save the breed from extinction. 



We are glad to have the pleasure of congratulating the editor 

 of the Zoological Record on the completion of the volume for 

 1900. Year by year his task grows more onerous, the volume 

 before us exceeding its predecessor by 180 pages. \"ery notice- 

 able is the length of the list of new generic and subgeneric 

 names, which contains no less than 2102 entries, the maximum 

 having been previously 1707, in 1S95. The increase in the 

 bulk of the volume is largely due to the insect record, which 

 comprises 354 pages against 276 in 1899. The yearly growth 

 in the size of the volume is, of course, largely to be attributed 

 to the practice of naming local races of animals, which has 

 come so largely into vogue of late. The various recorders 

 appear to have done their work with great care and thorough- 

 ness, although we notice in the mammal part that one paper 

 (No. 200) is credited to a writer other than its author. Uni- 

 formity in regard to the "introduction" to the different 

 "records" is still a desideratum, this important element being 

 altogether omitted in some instances, while in one case it has 

 been allowed to reach an altogether disproportionate length. 

 It is a decided improvement in the "get-up " that in this year's 

 issue the edges have been cut. We are glad to hear that there 

 is a good prospect of the promised " index volume " of generic 

 names making its appearance early in the year. 



None have laboured more earnestly on the land and freshwater 

 Mollusca of Pleistocene and recent times in Britain than Messrs. 

 A. S. Kennard and B. B. Woodward. Their latest work, "The 

 Post-Pliocene Non-Marine Mollusca of the South of England," 

 has just been published by the Geologists' Association {Proc. 

 vol. xvii. November 1 901). In this the lists from various localities 

 have been carefully checked and revised whenever possible from 

 an examination of the actual specimens recorded. Doubtful 

 records are omitted from the general list, in which are tabulated 

 the species from seven Pleistocene and thirteen Holocene 

 localities. There is also a column showing the species which 

 occur in Pliocene deposits, and another giving all the living 

 Biitish species. Of the 139 living species no less than 129 occur 

 in the south of England, and of the ten extinct furms seven have 

 been found in the same area. The authors have expressed their 

 opinion that the Pleistocene molluscan fauna was a finer one 

 than that of to-day. The non-marine Mollusca have reached 

 this country from various sources. In their opinion a large 

 number are boreal, and of these some travelled hither along the 

 now sunken land to the north of Scotland, whilst others may 

 have journeyed through Siberia and the Continent ; some have 

 come from the south by the old land connection between England 

 and the Continent ; while others, the so-called Lusitanian forms, 

 have reached us from south-west Europe ; a few species may be 

 endemic. Some changes in nomenclature are noted, but the 

 authors justly remark that the identity of the shell is of more 



