June 12, 1890] 



NATURE 



167 



Sanitary Science by the Grocers' Company. The election will 

 take place about August 26. Candidates are requested to apply 

 to Prof. Roy, 2 Wollaston Road, Cambridge, for information. 

 The Studentship is of the annual value of ;iC2oo, or of such 

 larger sum, not exceeding £yx), as the managers shall from time 

 to time determine ; and is tenable for three years. The Student 

 is required to devote himself during the tenure of the Studentship 

 to original pathological research. Dr. Hunter's tenure has 

 been marked by his elaborate and valuable researches on per- 

 nicious anaemia. 



The Professor of Mineralogy (Prof. Lewis) proposes to give a 

 course of elementary lectures on crystallography in the long 

 vacation, beginning on Tuesday, July 8, at 9 a.m. There will 

 also be a practical course on crystallography given by the 

 Demonstrator, beginning on the same day. Fees for lectures 

 £\ \s. ; for demonstrations £^ 2s. 



The Special Board for Biology and Geology have nominated 

 Miss L. Ackroyd (Newnham College) to occupy the University 

 table at the Laboratory of the Marine Biological Association for 

 one month during the year 1890. 



The Mechanical Workshops Enquiry Syndicate were on 

 Thursday, June 5, empowered by a large majority of the Senate 

 to inquire into the conditions and expense of establishing a 

 definite school of engineering in the University. 



The number of persons matriculated during the current aca- 

 demical year was on May 29 brought up to 1027, the largest 

 number on record. 



At a meeting of the Council of the Cambridge Philosophical 

 Society on Monday, June 2, it was decided, in accordance with 

 the Reports of the adjudicators. Sir W. Thomson, Lord Rayleigh, 

 and Prof. G. IL Darwin, to award the Hopkins Prize for the 

 period 1883-85 to W. M. Hicks, F.R.S., for his memoir upon 

 the "Theory of Vortex Rings " (Phil. Trans., 1885) and for his 

 earlier memoirs upon related subjects ; also to award the 

 Hopkins Prize for the period 1886 88 to Horace Lamb, 

 F.R.S., for his paper on "Ellipsoidal Current Sheets" (Phil. 

 Trans., 1887} and for his numerous othei papers on mathematical 

 physics. 



Prof. J. J. Thojison announces that a course of demonstra- 

 tions in practical physics, suitable for students who intend taking 

 the Natural Sciences Tripos after passing Part I. of the Mathe- 

 matical Tripos, will be given during the Long Vacation in the 

 Cavendish Laboratory on Mondays, Wednesdays, and Fridays, 

 at 10 a.m., commencing July 9. Students wishing to attend 

 the course are requested to send in their names to Prof, Thomson 

 before the end of the term. 



The Observatory Syndicate publish in the Reporter (June 10, 

 1890) their record of proceedings for May 27, 1889, to May 26, 

 1890. The astronomical work of observation and reduction has 

 been steadily carrried out, and the report is not marked by any 

 eventful feature. 



Dr. D. MacAlister and Prof. Roy have been appointed to 

 represent the University at the Tenth International Medical 

 Congress at Berlin. 



The General Board of Studies, with a view to recruiting the 

 finances of the University, especially in the scientific depart- 

 ments, propose to raise thi examination and other fees payable 

 by students. As a commencement they propose that the aggre- 

 gate fees to be paid for the six M.B. examinations be raised from 

 eight guineas to twelve. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 5. — "Account of Recent Pendulum 

 Operations for determining the Relative Force of Gravity at the 

 Kew and Greenwich Observatories." By General Walker, 

 C.B.. F.R.S., LL.D. 



It is well known that a series of pendulum observations was 

 carried on in India, during the years 1865 to 1873, with two in- 

 variable pendulums, the property of the Royal Society. The 

 Observatory of the Royal Society at Kew was chosen as the base 

 station of the operations, and the pendulums were swung there 

 before being sent out to India, and again on their return from 

 India. With a view to connecting the observations with those 

 which had already been taken with other pendulums in other 

 parts of the world, it was intended, on the return of the pendu- 

 lums from India, to swing them at the Royal Observatory at 

 Greenwich, which wa> a well-established pendulum station, ob- 

 served at by General Sir Edward Sabine, the Russian Admiral 

 Liitke, and others. But when the time arrived for making the 



NO. 1076, VOL. 42] 



observations at the Greenwich Observatory, such extensive pre- 

 parations were being made there for the equipment of expeditions 

 for the observation of the approaching transit of Venus that na 

 room was available for the pendulum operations. It was, there 

 fore, decided to make the connection with Kew by swinging at 

 Kew Kater's convertible pendulum, for determining the absolute 

 length of the seconds' pendulum, which had been swung 40 years 

 previously at Greenwich by General Sabine. This being done, 

 the length of the seconds' pendulum at Kew was found to be 

 0-0027 of an inch greater than the length which had been pre- 

 viously determined at Greenwich, and consequently that the 

 daily vibration number was three vibrations greater at Kew than 

 at Greenwich. The difference, however, was far too large to be 

 admissible, as the Observatories are nearly in the same latitude, 

 and differ very slightly in height. 



In 1881, Colonel Herschel, R.E., was deputed by the Secre- 

 tary of State for India to take pendulum observations at the 

 two Observatories, and at the old pendulum station in London, 

 and als3 at some stations in America, with a view to improving 

 and strengthening the connection between the observations in 

 India and those in other parts of the world. On completing his 

 work in America, he handed over the three pendulums which he 

 had employed to officers of the United States Coast and Geodetic 

 Survey, by whom they were taken round the world, and swung 

 at Auckland, Sydney, Singapore, Tokio, San Francisco, and 

 finally at Colonel Herschel's terminal station at Washington. 



But when the observations came to be finally reduced, it was 

 found that the difference between Colonel Herschel's results at 

 Kew and Greenwich, as shown independently by the three 

 pendulums, had an extreme range of about seven vibrations in 

 the daily vibration number. The cause of these differences was 

 mysterious and inexplicable, and there was no alternative but to 

 swing the pendulums a second time at the two Observatories. 



The revisionary work was undertaken by the Observatory staff 

 at each place, in such intervals of leisure as they could obtain 

 from their regular operations. The final results, by the three 

 pendulums, make the vibration number at Kew in excess of that 

 at Greenwich by 1*56, i "50, and 0-59, giving an average excess 

 of I •22. 



The correction to this quantity for the excess of height of the 

 Greenwich over the Kew Observatory is - 0*58. Thus, the 

 revisionary operations, reduced to the mean sea-level, make the 

 excess of Kew over Greenwich = o'64 of a vibration, which 

 may be accepted as very fairly probable. 



Royal Microscopical Society, May 21. — Mr. James 

 Glaisher, F.R.S., Vice-President, in the chair.— Mr. Mayall 

 referred to the donation, by the Messrs. Trainini Bros., opticians 

 of Brescia, of an early form of achromatic microscope objective, 

 constructed by the late Bernardini Marzoli, Curator of the 

 Physical Laboratory of the Lyceum of Brescia. The objective 

 was a cemented combination, and was described and figured in the 

 "Commentari della Accademia di Scienze" of Brescia in 1808. 

 This and other works and documents in proof of its authenticity 

 were exhibited. — Mr. Mayall exhibited on behalf of Mr. P. 

 Vallance an eyepiece similar to that shown at the previous 

 meeting by Mr. Goodwin. It was one of two constructed by 

 Mr. Murrell nearly forty years ago, and was provided with a 

 screw which enabled the compound eye lens to be adjusted with 

 reference to the field lens through a space of nearly h inch. 

 — Mr. E. M. Nelson read a paper on micrometers, in the course 

 of which he described a new micrometer made for him by Messrs. 

 Powell and Lealand. The subject was illustrated by a drawing 

 upon the board, and the micrometer attached to a microscope 

 and lamp was handed round.— Mr. Thomas Comber's paper 

 on a simple form of heliostat, and its application to photomicro- 

 graphy, was read. Apart from the question of the extreme 

 simplicity of the heliostat, which was mainly due to limiting the 

 reflection of the mirror to the polar direction and deflecting the 

 pencil in the horizontal direction in the axis of the microscope, 

 by means of a fixed mirror placed at half the angle of the 

 latitude above the heliostat mirror, Mr. Comber had rendered 

 important service to photomicrography by showing how the 

 heliostat might be placed close to the microscope so that the 

 error due to slight inaccuracy of the adjustment of the heliostat 

 might escape the optical leverage which took place when the 

 reflected beam was made to travel through a considerable space. 



Paris. 

 Academy of Sciences, June 2.— M. Hermite in the chair. 

 — On the application of a double plane mirror to the ])recise 



