50 
OUR ASTRONOMICAL COLUMN. 
THe VARIABLE NEBULA IN CORONA AUSTRALIS.—A 
somewhat extended investigation of this remarkable 
object—N.G.C. 6729—has been made at Helwan with 
the Reynolds 30 in. reflector, and a brief account of 
the observations, with illustrations, has been given by 
J. H. Reynolds (Monthly Notices, R.A.S., vol. Ixxvi., 
p- 645). The thirty-seven photographs talken during 
1914 and 1915 clearly demonstrate that the nebula is 
variable in form as well as in brightness, and it seems 
NATURE 
probable that its variability is closely related to that of | 
the variable star R Coronz Australis, to which it 
appears to be attached. The appearance is such as 
might be expected if the nebulous matter was dis- 
charged from the star when at its maximum bright- 
ness and illuminated by it. 
Further particulars are given by Mr. Knox Shaw, 
who took the photographs. The forms of the nebula 
can be classified into seven types, ranging from the 
first, in which the nebula is very bright and attached 
to the star, to the seventh, where the nebula is very 
faint and entirely detached. There is, however, no 
simple relation between the form of the nebula and 
the magnitude of the star; the nebula is brightest 
when the star is brightest, but is not always of the 
same form for a given magnitude of the star. It 
seems quite possible that the apparently imperfect 
correspondence between the variations of the nebula 
and those of the star may be caused by the presence 
of absorbing matter lying between them and the earth. 
If this absorbing matter were of varying thickness and 
in motion, it would naturally complicate the pheno- 
mena, but it is not suggested that this is the main 
cause of the variability. 
Proper Motions By THE BLINK-MICROSCOPE.—A 
further report on the use of the blink-microscope (see 
Nature, vol. xcvi., pp. 237 and 438) in the detection 
and measurement of proper motions has been issued 
by Mr. Innes (Union Observatory Circular, No. 35). 
The greater part of the report refers to the comparison 
of eight astrographic plates taken at Greenwich, at 
intervals approximating to twenty years, and forty-three 
proper motions of stars ranging in magnitude from 
7-1 to 13:5 are tabulated. As an indication of the 
rapidity of work by this method, Mr. Innes states that 
the investigation of the eight regions, including the 
identifications and reductions, occupied only twenty- 
four hours, although there was no attempt to make a 
record. Every pair of plates confirmed the impression 
that the vast majority of stars, bright and faint, are 
relatively fixed, and the measures were made on this 
assumption, the numerical work then being very slight. 
If plates are taken with a view to their ultimate 
examination by the blink-microscope, Mr. Innes con- 
siders that long exposures should be given, as crowded 
regions are a great advantage. Triple images are un- 
necessary, and double images are also superfluous if a 
third plate be available. 
Tue Preriop or U Cepnet.—aA discussion of Wen- 
dell’s observations of this well-known eclipsing vari- 
able has been undertaken by Martha B. Shapley 
(Astrophysical Journal, vol. xliv., p. 51). The observa- 
tions were made at Harvard during the years 1895- 
1912 with a polarising photometer, the total number 
of comparisons being 17,296; they have a special value 
because the instrument, method of observing, and 
comparison star were the same throughout this long 
period. As the light at minimum is constant for about 
two hours, Wendell observed mainly the steepest part 
of the ascending or descending branch, and in most 
cases the time at which the star was at a specified 
magnitude—say, 8.40—can be determined from the 
observations with an uncertainty of less than a minute. 
Variations in the mean phases of both steep branches 
NO. 2447, VOL. 98] 
fst 
[SEPTEMBER 21, 1916 
are apparent, and there is evidence that the variation 
is not in the duration of minimum, nor due to vari- 
ability of the comparison star, but a definite change 
in the light period. When all the observations since 
' the time of discovery in 1880 are considered, it is 
| evident that they are not satisfied either by Chandler’s 
elements (1903) or by those of Wendell (1909). The 
latter serve best as a working formula at the present 
time, but would probably predict the minima too early. 
The variations are apparently very complex, and no 
attempt has yet been made to obtain an analytical 
expression for them. Wendell’s formula is 
Min. =J.D. 2407890-3007 + 2-4928840d. E 
with zero phase at the midpoint of minimum light. 
The mean magnitude at minimum is 9-14, and at 
maximum 6°81. 
MR. JOHN ANGELL. 
cy September g there passed away in the person of 
Mr. John Angell a figure notable in the educa- 
tional world of Manchester. He was born in 
London in 1824, and in his early educational career 
was chemical assistant to Prof. Thos. Graham, 
F.R.S., professor of chemistry in University College, 
London, and was hon. secretary to the Birkbeck 
_ School Committee, whose school was the first estab- 
lished in Great Britain with the object of. demonstrat- 
ing both the desirability and the possibility of teach- 
ing soundly and rationally the elements of science 
as leading everyday subjects in the ordinary day 
school. In 1852 he accepted an appointment at ‘the 
Salford Mechanics’ Institute as head of the Boys’ 
School established therein, and five years later 
| became the organiser of the day and evening classes of 
the Manchester Mechanics’ Institution, then established 
in a new and commodious building in that city, 
where he remained for twelve years, resigning his 
position in 1869 to accept the senior science master- 
‘ship in the Manchester Grammar School, then under 
the vigorous direction of Mr. F. W. Walker, after- 
wards master of St. Paul’s School, London. Mr. 
Angell remained at. this post for eighteen years, 
during which period he greatly raised the reputa- 
tion of the school by his energetic and intelligent 
teaching of science, especially in the subject of 
physics. He was an enthusiastic disciple of George 
Combe, whose teaching, as exhibited in his es 
“The Constitution of Man,” as he said, ‘‘ completely 
revolutionised the course of my life.” He was an 
ardent and enlightened exponent of the ‘‘Socratic’” 
method of instruction, which he applied with much 
success in the courses he gave in chemistry, physics, 
and physiology to day and evening pupils during his 
career at the Manchester Mechanics’ Institution. In 
1868 the Institution was visited by a French Imperial 
Commission appointed to visit and report upon 
secondary education in England and Scotland. In 
its report it has nothing but praise for the 
methods of teaching in use. “If he selects a re- 
agent, it is because some pupil suggested it; if he 
obtains a gas in his analysis, he has already caused 
his students to predict its nature. . . . ‘ My object,” 
as this excellent teacher told us, ‘is to train the 
intellect through the study of science.’ His work 
as a teacher received the approval of such men as 
Drs. Joule and Angus Smith, and Profs. Clifton, 
Williamson, and Roscoe. He ceased his duties as 
a teacher in 1887, but continued his keen interest 
in scientific subjects in association with many of 
the literary and scientific societies of Manchester of 
which he was an active member almost to the day 
of his death’ at the ripe age of ninety-two. He was 
the author of many once widely used science text- 
hooks. : 
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