January 3, 1901] 



NATURE 



235 



the evolution of Mtcraster, so that in successive stages 

 of the Chalk he finds variations in the structure of 

 the tests, variations indeed which " are so marked 

 that one can tell by their aid from what zone a 

 Micraster is derived." As passage-forms and mutations 

 form the bulk of the genus, it is necessary to mass cer- 

 tain obviously aUied forms into groups which will admit 

 of the zoological continuity being exemplified and the 

 zonal peculiarities noted. This is the plan adopted by 

 Dr. Rowe, and it certainly appears most philosophical 

 to take a series of specimens rather than an individual as 

 the foundation for a zonal specific type ; and to group 

 rather than to try and separate so many forms. It is 

 satisfactory to learn that the detailed zoological work 

 carried out by Dr. Rowe bears witness to the great value 

 of the palasontological zones which were broadly marked 

 out in the chalk of this country nearly twenty-five years 

 ago by Dr. Charles Barrois. 



There is no doubt that the careful collecting of fossils 

 from definite horizons, and from horizons in definite 

 sequence, is of the utmost importance in advancing 

 palseontological knowledge. Such work, as a rule, re- 

 quires prolonged labour, otherwise the conclusions are 

 worse than useless. Now, by close research, it is possible 

 to trace out the successive modifications that occur in 

 stratigraphic sequence, and this has been attempted with 

 the Graptolites, and with several groups of Mollusca and 

 Brachiopoda, as well as with Echinodermata. Even in 

 so variable a group as the Oysters, it is affirmed by 

 Messrs. R. T. Hill and T. W. Vaughan {^Bulletin U.S. 

 Geol. Survey, No. 151) that these organic remains possess 

 very distinct specific characters, have definite geologic 

 horizons and are of the greatest value in stratigraphic 

 work. Their value, moreover, may be not merely 

 scientific, but also of some benefit to humanity. In- 

 stances have occurred in Texas where, by the aid of 

 these fossils, brought up from great depths in diamond- 

 drill cores, cities upon the point of abandoning the 

 attempt to procure artesian water have been warranted 

 in drilling a few feet farther, and with success. 



Views on the duration of geological time have occu- 

 pied a considerable amount of letterpress during the past 

 fifty years, and during the past i&ft years the subject 

 has been discussed by Mr. G. K. Gilbert, Mr. J. G. 

 Goodchild, Sir A. Geikie, Prof J. Joly, and Prof. W. J. 

 Sollas. 



Mr. Gilbert would look to the influence of precessional 

 changes and to the periodic modification of the climatic 

 conditions of the two hemispheres. Contrasted phases 

 of climate would thus occur every 10,500 years, and such 

 changes should be looked for in the strata. Indications 

 of moist or dry climates, of the increase or decrease of 

 glaciers, and of the local fluctuations of sea-level as 

 affecting the character and extent of strata are the indices 

 to which he would appeal. 



Prof. Joly, arguing from the amount of sodium at pre- 

 sent contained in the waters of the ocean and the amount 

 annually supplied by rivers, claims that a period of 

 between eighty and ninety millions of years has elapsed 

 since the land first became exposed to denuding agencies. 

 Sodium, as stated by Prof. Joly, is the only dissolved 

 substance of which the ocean has retained substantially 

 the whole amount committed to it by the solvent denu- 

 dation of geological time. 



Prof. Eug. Dubois, dealing with the circulation of car- 

 bonate of lime, believes that the real lapse of time since 

 the formation of a solid crust and the appearance of life 

 upon the globe may be more than one thousand million 

 years. 



Mr. J. G. Goodchild in 1897 also argued that the more 

 trustworthy data relating to the time of formation of 

 marine strata were furnished by deposits of organico- 

 chemical origin. He concluded that over seven hundred 



NO. 1627, VOL. 63] 



million years would be required since the commencement 

 of the Cambrian period. 



Although the conclusions arrived at by investigators 

 are widely at variance, it is not improbable that some 

 trustworthy data may in time be gained by the different 

 methods of research advocated by Gilbert and by Joly. 

 As lately remarked by Sir A. Geikie, progress in geology 

 will be best made by the adoption of more precise 

 methods of research and by a hearty co-operation among 

 geologists in all parts of the world ; and Prof Sollas well 

 observed in his address at Bradford that "our science 

 has become evolutional, and in the transformation has 

 grown more comprehensive." The work of the palaeon- 

 tologist must be supported by very detailed local field- 

 work, work which at present is very much in its infancy. 

 Such work will help in the grand story of " the science 

 of the earth," a story whose materials can only be 

 gathered together by the patient local toiler ; while he or 

 she may well be content to see the results worked up by 

 those who by training and opportunity are able to take a 

 comprehensive view of the earth as a whole. 



H. B. W. 



LORD ARMSTRONG, F.R.S. 



THE death of Lord Armstrong on Thursday last, in 

 his ninety-first year, will be regretted in the world 

 of engineering and applied science. To the general 

 public he was best known as a manufacturer of muni- 

 tions of war, but engineers will remember him more for 

 his developments of hydraulic machinery, and in science 

 his name will be associated with the discussion of the 

 duration of our coal fields, and the development, and 

 discharge phenomena, of statical electricity. 



William George Armstrong was born at Newcastle- 

 upon-Tyne in 1 8 10, and educated at a school at Bishop 

 Auckland. He adopted the law as a profession, and 

 became a partner in a firm of solicitors ; but a strong 

 bent for scientific pursuits led him to study mechanics 

 with more interest than law and eventually diverted him 

 into another career. Early in life he began investiga- 

 tions of electrical subjects, which resulted in the inven- 

 tion of the hydro-electric machine familiar to all readers 

 of text-books of electricity. The circumstances which 

 suggested this novel electrical machine are well known. 

 The workmen at a colliery near Newcastle had observed 

 that when steam was blowing off from the high-pressure 

 boiler, a smart shock was received if the safety valve 

 was touched, and sparks could be seen. An investiga- 

 tion of the phenomena showed Mr. Armstrong that the 

 boiler was insulated on a dry seating, and the friction of 

 the water particles against the sides of the orifice 

 through which it was escaping caused a development of 

 electricity. On this discovery he based the construction 

 of his hydro-electric machine, which at that time formed 

 the most powerful means of generating frictional 

 electricity. It consisted essentially of an insulated boiler, 

 from which steam at high pressure was allowed to 

 escape through nozzles of peculiar construction. For 

 this he was elected a Fellow of the Royal Society in 

 1846, while still comparatively a young man. 



Another electrical research for which Lord Armstrong 

 will be remembered was concerned with electric move- 

 ment in air and water, and it culminated in the publica- 

 tion of an elaborate volume on the subject in 1897. In 

 this work a striking experiment, performed with the 

 hydro-electric machine half a century earlier, was made 

 the starting-point of a valuable research on the nature of 

 electric discharges. Two glasses of distilled water were 

 placed near together, and a thread of cotton, which was 

 coiled up in the one, had its free end placed so as to dip 

 in the other. On negatively electrifying the glass of 



