14: 



NA TURE 



[December i i, 1902 



Dr. Roget's paper seems to be almost unknown, and it is only 

 in these modern days that the computations for which he in- 

 vented the rule have to be frequently made. — Prof. H. L. 

 Callendar exhibited a lecture experiment for the determination 

 of the mechanical equivalent of heat. The experiment was 

 carried out with a im lifted form of the apparatus exhibited and 

 described by Prof. Callendar at the meeting of the Physical 

 Society held on June 20. 



Geological Society, November 19.— Prof. Charles Lap- 

 worth, F.R.S., president, in the chair. — The Semna Cataract 

 or Rapid of the Nile, a study in river-erosion, by Dr. John Ball. 

 Inscriptions placed on the rocks at Semna, between the second 

 and third cataracts, under the twelfth and thirteenth dynasties, 

 serve as a means of gauging the local changes due to river- 

 erosion during a period of about 4200 years. Horner, in 1850, 

 came to the conclusion that "the only hypothesis which could 

 meet the requirements of the facts observed would be either 

 the wearing away of a reef or barrier at the place in question — 

 a process requiring too long a period — or the existence at some 

 distant period of a dam or barrier, formed perhaps by a landslip 

 of the banks, at some narrow gorge in the river's track below 

 Semna." The author is in favour of the former explanation. 

 Rapid erosion with the formation of pot-holes is observed to 

 be now taking place, and the author calculates that if 200 

 cubic metres (approximately 500 tons) of rock per year has 

 been removed from the barrier, the lowering of it would amount 

 to 2 millimetres a year, or in 4200 -years 7 '9 metres, the depth 

 of the present river below the lowest group of inscriptions 

 dating from the time of Amenemhat III. The yearly discharge 

 of the Nile past Semna is nearly 100,000 million tons of water, 

 and the author considers that the removal of 500 tons of rock 

 under existing conditions in a year is not only not impossible, 

 but highly probable, as all this erosion only amounts to 5 milli- 

 grams of rock per ton of silt-laden water. This erosion is com- 

 pared with the classic instance of the River Simeto in Sicily. 

 At Assuan and Silsilla, the river has suffered considerable lower- 

 ing within geologically recent times, probably brought about 

 by the removal of long pre-existent hard barriers. The sluices 

 of the new dam at Assuan may in the future give a quantitative 

 determination of silt-erosion in granite, and it would appear to 

 be not difficult to ascertain at Semna the rate of pot-holing. 

 The formation of new potholes l\ feet deep, in an artificial 

 channel in rock in Sweden, has been observed to take place in 

 eight or nine years, and the author hopes in future to attempt 

 some measurements of this kind at Semna. — Geological 

 lotes on the North-West Provinces (Himalayan) of India, by 

 Mr. Francis J. Stephens. The country examined extends in a 

 north-westerly direction across the line of strike, from the 

 borders of Nepal and South-eastern Rumaon to north of the 

 Alakmunda River in the vicinity of Badrinath and the Marra 

 Pass. The summary of the author's observations leads him to 

 "suppose that there are at least three distinct limestone or cal- 

 careous series in Kumaon and Garhwal, and that schists and 

 quartzites. with several isolated patches of granitic rock, form a 

 large part of the remaining formations."— Tin and tourma- 

 line, by Mr. Donald A. MacAlister. The author gives a 

 possible explanation of the reactions by which tin oxide could 

 be separated from solution in magmas containing alkaline 

 borates. 



Mineralogical Society, November 18. — Dr. Hugo Muller, 

 F.R.S., president, in the chair. — Mr. F. E. Lamplough con- 

 tributed a note on proustite crystals, on some of which an 

 unusual trigonal pyramid {733! is the dominant form, and on 

 others the pyramid {944"} These forms are associated with 

 rjioo}, e)on}, 2'j2oTJ, aJioTJ, and in one case with {if. 7.7.J . 

 — Prof. W. J. Lewis described crystals of mispickel and iron 

 pyrites from the Binnenthal, and crystals of quartz and sphene 

 from the Ofenhorn. — Mr. R. H. Solly gave an account of various 

 minerals from the Lengenbach, Binnenthal. These included 

 large crystals of baumhauerite differing in habit from those 

 previously described by him and exhibiting several new forms, 

 an unique crystal of binnite weighing more than 8 grams, and fine 

 specimens of dufrenoysite partially covered by minute crystals of 

 seligmannite. On the latter, ten new forms were observed, and 

 from measurements made on twelve brilliant crystals the axial 

 ratios were determined to be a : b :c=oq2^2 : I :08733s. 

 The presence of copper was detected and the streak was chocolate- 

 brown. Mr. Solly also discussed the crystallography of a pre- 

 sumably new mineral from the Lengenbach, five minute but 

 brilliant crystals of which were found on a crystal of rathite. In 



NO. 1728, VOL. 67] 



these crystals, no plane or axis of symmetry could be determined, 

 and each crystal was grown in a different position. — Mr. G. F. 

 Herbert Smith exhibited a special form of protractor, and described 

 the method of using it for plotting poles on a sphere in gnomonic 

 projection and for determining the angles between poles and 

 between zones graphically from the diagram. — Mr. G. T. Prior 

 discussed the connection between the molecular volumes and 

 chemical composition of some crystallographically similar 

 minerals. He pointed out the chemical relationships (similarity 

 in form of the chemical molecule with approximately the same 

 number of atoms) of the members of the hamlinite-beudantite- 

 jarosite group of rhombohedral minerals and showed that the 

 molecular volumes exhibited an approach to equality. In the 

 case of several sets of crystallographically-similar minerals, it was 

 found that when the chemical formula; were made similar in form 

 by taking suitable multiples of the simplest formula;, then the 

 molecular volumes calculated for these new formulx' were ap- 

 proximately equal. On this principle, from the crystallographic 

 similarity of rutile to zircon, of anatase to calomel and of 

 brookite to tantalite and wolfram, the following formuke for the 

 three forms of titanic acid were deduced, viz. rutile (Ti.,0 4 ), 

 anatase (Ti 4 O s l, brookite (Ti 6 12 ). — Mr. Prior also contributed 

 a note on phonolitic rocks from St. Helena and Ascension. 

 These were compared with similar rocks from the Great Rift 

 Valley and from Abyssinia, and the striking uniformity of the 

 volcanic rocks of the African continent was pointed out. It was 

 suggested that this was only a part of a wider generalisation 

 according to which the volcanic eruptions of the great Atlantic 

 volcanic chain (including its two transverse European branches 

 and the minor chain down the east side of Africa) are charac- 

 terised by the association of basalts and alkali-rich phonolitic 

 rocks, whereas andesites are the prevailing lavas of the two great 

 Pacific chains. — Mr. L. J. Spencer described the crystalline form 

 of carbides and silicides of iron and manganese, crystals of which 

 had been placed at his disposal by Mr. J. E. Stead. He showed 

 that crystals of the metallurgical products, spiegeleisen, ferro- 

 manganese and silico-ferro-manganese, of which the general 

 chemical formula is (Fe,Mn) 3 (C,Si), are of two kinds — (1) 

 rhombic with a prism-angle of 67A ; (2) anorthic with a prism- 

 angle of ahout 6o". 



Linnean Society, November 20. — Prof S. H. Vines, F.R.S., 

 president, in the chair. — Mr. R. Morton Middleton, gave 

 an account of the dissertation by Linnaeus on Siren laccrtina, 

 annotated by the author, which he had found in a dealers pos- 

 session and since then had been presented to the Society by the 

 treasurer. — Mr. \V. C. Worsdell showed a series of anomalous 

 virescent flowers of Hclenium autumnale, six strong plants 

 in the garden at Friar Park, Henley, the residence of the 

 treasurer, being thus affected. — Mr. H. E. H. Smedley ex- 

 hibited large wax models of the fossil seeds of Stephanospermum 

 akenioides and Lagenostoma, the latter occurring in the Lower 

 Coal-measures of Lancashire ; he also showed a model of a recent 

 Cycad for comparison. — Rev. T. R. R. Stebbing, F.R.S., V.P., 

 having taken the chair, the president reminded the Society that 

 exactly a year ago he had the honour of giving an account of 

 some observations upon the action of the enzyme contained in 

 the secretion of Nepenthes. That enzyme, he then explained, 

 not only possesses the property of pep'onising the higher 

 proteids (e.g. fibrin), but is also proteolytic, decomposing the 

 proteid molecule into non-proteid nitrogenous substances such 

 as leucin and tryptophane. The proof of this is afforded by the 

 fact that liquids containing proteids that have undergone digestion 

 give the tryptophane reaction ; that is, a pink or violet colour 

 on the addition of chlorine-water. Since that time, many other 

 plants have been investigated with the object of ascertaining, (1) 

 whether or not a digestive enzyme were present, and (2) of 

 determining the nature of its action. In almost all cases, the 

 presence of a proteolytic enzyme has been demonstrated. The 

 experiments definitely establish the fact that an enzyme which 

 actively proteolyses the simpler forms of proteid is present in 

 all parts of the plant-body. But the question as to the precise 

 nature of this enzyme still remains to be answered. Where 

 proteolysis is accompanied by peptonisation, it may be inferred 

 that the enzyme is allied to the trypsin of the animal body. 

 Where no peptonisation, but only proteolysis, can be detected, 

 it seems probable that the enzyme is allied to the erepsin recently 

 discovered by Cohnheim in the small intestine. Possibly more 

 than one enzyme may be active in certain cases. The conclusions 

 arrived at depend entirely upon the trust to be placed upon the 

 tryptophane reaction as evidence of proteolysis. From what is 



