il NATURE 
[JANUARY 6, 1923 


NOTICE. 
The present issue of NATURE begins a new 
volume; the time is therefore opportune to 
begin subscriptions. The subscription rates 
are to be found on p. vii. 
Proof copies of the accompanying photo- 
gravure plate portrait of Prof. Lorentz, suitable 
for framing, are obtainable for 5s., or by 
post for 5s. 6d. 
OFFICE OF NATURE, 
ST. MARTIN’S STREET, W.C.2. 


THE SIR JOHN CASS TECHNICAL INSTITUTE, 
Jewry Street, Aldgate, E.C.3. 
Tue following Special Courses of Instruction will be given 
during the Lent Term, 1923 :— 
THE MATHEMATICAL THEORY AND APPLICATIONS 
OF STATISTICS. 
By E. C. Snow, M.A., D.Sc. 
A Course of Ten Lectures on the modern mathematical 
methods of dealing with statistical data in social, educational, 
economic, meteorological and medical problems, suitable to 
teachers and to students of economics, meteorology and medicine. 
Facilities will be given to students who wish to undertake special 
investigations and research work on subjects associated with the 
course of instruction. 
Fridays, from 7 to 9 P.M. 
The First Lecture of the Course will be given on Friday, 
January 12, 1923. 
ALTERNATING CURRENTS AND ELECTRICAL 
OSCILLATIONS. 
By D. Owen, B.A., D.Sc., F.Inst.P. 
A Course of Ten Lectures accompanied by Practical Demon- 
strations, and intended for post-graduate students and those 
otherwise qualified to pursue this branch of electrical science and 
its applications in wireless telegraphy and telephony. 
Tuesdays, from 7 to 8.30 P,M. 
The First Lecture of the Course will be given on Tuesday, 
January 9, 1923. F 
Detailed Syllabus of the Courses may be had upon application 
to the Office of the Institute, or by letter to the PRINCIPAL, 
Cuar.Les A. KEANE, D.Sc., Ph.D., F.1:C, 

IMPERIAL COLLEGE OF SCIENCE 
AND TECHNOLOGY, 
SOUTH KENSINGTON, S.W.7. 
DEPARTMENT OF OPTICAL ENGINEERING 
AND APPLIED OPTICS. 
The usual Classes are being continued during the SPRING TERM, and 
in addition the following will be given :-— 
CoLour AND ITs MEASUREMENT.—A Course of TEN Weekly Experi- 
mental Lectures beginning on Tuesday, January 16, at 6.30 P.M. will be 
given by Dr. L. C. MARTIN. 
Tue MECHANICAL DesiGn oF THE Common MicroscopE.—A Course 
of SIX Weekly Lectures will be given by Professor POLLARD on Thursday 
at 6 P.M., commencing January 18. 
For further particulars and for admission tickets apply to the REGISTRAR 
at the above address. 
The Director is open to receive applications from students and_ others 
desirous of carrying out research work in the Laboratories. 

THE GENERAL DISCUSSIONS OF 
THE FARADAY SOCIETY. 
The SECRETARY will send on application the latest list of available 
REPRINTS.—10 Essex Street, London, W.C.2. 



CHELSEA POLYTECHNIC, 
CHELSEA, S.W.3. 
Day and Evening Courses in Science under Recognised Teachers 
of London University. 
I. INDUSTRIAL CHEMISTRY DEPARTMENT. 
Technical Courses in Analytical and Manufacturing Chemistry, 
Pharmacy, Food and Drugs, A.I.C. Courses, Metallurgy, Assaying, 
Foundry Work, Research. 
I. INDUSTRIAL PHYSICS DEPARTMENT. 
Practical work in General Physics, Applications to seat 
Metrology, Calorimetry, Illumination, Acoustics, Electri 
Measurement, Research. 
lll. BIOLOGICAL. AND GEOLOGICAL DEPARTMENT. 
Courses for B.Sc., etc., in Botany, Geology, Mineralogy, Zoology, 
Special Courses in Bio-chemistry, Bio-physics, Bacteriology, 
Physiology, Hygiene, Entomology, Plant Pathology. Course for 
Tropical Planters, Research. 
Lent Term begins January 9, 1923. 
SIDNEY SKINNER, M.A. 
Principal. 
BIRKBECK GOLLECE. 
(UNIVERSITY OF LONDON.) 
Principtal—GEORGE SENTER, D.Sc., Ph.D., F.I.C. 
EVENING COURSES for the Degrees of the 
University of London in the Faculty of Science and 
for the Geography Diploma. 
Telephone: Kensington 8a9. 

Facilities are also provided during both day and 
evening for Post-Graduate and Research Work. 
Calendar, 1s.; by post, 1s. 5d. Prospectus free. 
For full particulars, apply to the SECRETARY, 
Birkbeck College, Fetter Lane, E.C.4. 
BATTERSEA POLYTECHNIC. 
Principal—* RoBERT H. Pickarp, D.Sc., F.R.S. 
University Courses, day and evening, under Recognised Teachers of 
the University of London are provided in Science, Engineering and Music. 
CHEMISTRY.—*J. Kenyon, D.Sc., F.1.C.; *J. L. Wuite. D.Se. 
PHYSICS.—*S. Maksu, B.Sc., Ph.D.; * A. E. Evans, B.Sc.; * J. F. 
Puivuts, B.A., B.Sc. 
MATHEMATICS.—* F. M. Saxe.py, M.Sc., B.A.; *F. W. Harvey, 
B.Sc., M.A.; * W. G. Bicktey, M.Sc. 
ENGINEERING.—*W. E, M. 
MECHANICAL AND CIVIL 
Curnock, M.Sc., B.Eng.; *J. B. SHaw, A.R.C.S., Wh.Ex.; *H. M. 
M.LE.E., 
Epmonps, B.Sc. ; * V. C. Daviss, B.Sc., A.M.I.Mech.E. 
A.Am.1.E.E.; *H. C. Mann, ‘A.M.I.E.E.; *H, W. HARTRIDGE, 

ELECTRICAL ENGINEERING.—*A. T. Dover, 
A.M.I.M.E.; * A. M. Parkinson, B.Sc., Eng. 
MUSIC.—* H. D. WETTON, Mus. Doc., F.R.C.O. 
* Denotes recognised teacher of University of London. 
There are also :— 
Day Technical College in Engineering and Science. Day Trainin 
College of Domestic Science. Day Department of Hygiene anil 
Physiology. Day School of Art and Crafts. 
Evening Courses in Engineering, Chemistry, Physics, Mathematics, 
Bacteriology, Chemical Engineering, Hygiene and Physiology, Art, 
Matriculation Subjects, Domestic Economy, Music, Physical Training. 
Hostels for Women Students. Large playing fields at Merton, 
APPOINTMENTS BOARD 
OF THE 
IMPERIAL COLLEGE OF SCIENCE 
AND TECHNOLOGY, 
SOUTH KENSINGTON, S.W.7. 

EMPLOYERS requiring men who have received a thorough training in” 
Science and Technology, and who are Diplomates or Associates of the 
Imperial College, or of one of its three constituent Colleges, are asked to 
make use of the services of the Board. No fees. 
The Imperial College includes The Royal College of Science, The Royal 
School of Mines, and The City and Guilds (Engineering) College. The 
Associates of the Colleges receive thorough training in Science and Tech- 
nology, including Aeronautics, Applied Optics and Optical Engineering, 
Biology, Chemical Technology, Chemistry (all branches), Engineering (all 
branches, including Metallurgy, Mining, Mining Geology and Oil Tech- 
nology), Geology, Mathematics and Mechanics, and Physics. } 

B.Sc. (LADY) wishes post as junior assistant 
in chemistry laboratory or as chemistry demonstrator. 6 months’ ex- 
perience. Box 43, c/o NaTurRE Office. 
