616 
NALORE 
~ [OcTOBER 26, 1899 
large if the imposed force has the same frequency as any of the 
natural vibrations of the bubble. 
When the bubble is long, as in an ordinary level, the result 
when such a coincidence is reached is that the long bubble is 
broken up into a number of small ones, but in the bicycle level 
the bubble was small and nearly spherical. 
The slowest natural vibration which a spherical bubl le is 
capable of is that in which it becomes alternately a prolate and 
oblate spheroid. 
It would take too long to enter in detail into the character of 
the deforming forces acting on the bubble. They are of two 
kinds, one depending on the acceleration and the other on the 
velocity. The former tends to make the bubble egg-shaped 
(z.e. big at one end and small at the other) to a degree propor- 
tionate to the acceleration; the latter involves the ratio of the 
cross section of the bubble and tube, and tends to make the 
bubble oblate as the velocity increases. 
When the impressed motion has the same period as the bubble, 
the latter will pass through its zero position in opposite phases. 
. Thus, if in moving forwards it is an oblate spheroid as it passes 
through the zero, it will be prolate half a period later when re- 
turning backwards through the same position, but both the 
deforming force and resistance to motion through the fluid 
which the bubble experiences when prolate are less than when 
it is oblate, so that there is a balance in favour of the oblate de- 
formation, which will tend to increase and perpetuate a vibration 
once started. 
Since the resistance experienced by the prolate form is less 
than oblate resistance, the excursion of the bubble will be 
greater in the first case than the last, with the result that in 
time it will move to such a position that the slope of the tube 
there supplies a force sufficient to balance the difference of resist- 
ance met with in moving in opposite directions. 
In the accompanying diagram the direction of the level tube 
is supposed to be at right angles to the abscissa axis, which 
represents the time of one oscillation. 
AA displacement of level tube; BB displacement of bubble 
relatively to the tube; cc deforming force depending on the 
velocity ; 1, 2, 3, &c., the forms assumed by the bubble at various 
phases. 
There is some particular ratio between the diameters of the | 
bubble and tube, and some absolute diameter of the tube, 
depending on the surface tension and density of the fluid, which 
gives the maximum displacement, but even an approximate 
analytical solution of the problem would present great 
difficulties. ; 
In. the level experimented on, the surface tension of the 
fluid employed was 27 (in C.G.S.) and density 88. 
The radius of the bubble was "142 cm. and that of the 
tube 23 cm. (rough measurements). 
A spherical bubble of the radius given if surrounded by an 
unlimited quantity of fluid of this surface tension and density 
would have for the frequency of its slowest natural vibration 
120 per second nearly (see Lamb, ‘‘ Hydrodynamics,” p. 463), 
but in the case under consideration the small distance between the 
sides of the bubble and tube must greatly diminish the frequency 
of this form of vibration. 
By experiment it was found that the greatest displacement 
occurred with a frequency between 40 and 50 per second, the 
bubble then being driven to the ends of the tube where the slope 
was about one in five. A. MALLock. 
3, Victoria Street, October 3. 
Rural Education. 
THE Countess of Warwick and Prof. Meldola are entitled to 
all praise for their zeal in establishing the School of Science at 
Bigods, to which reference was made in your issue of October 
5. There should, however, be some recognition of the similar 
NO. 1565, VOL. 60] 
work done by others in purely rural districts.. At Bruton, a 
village in Somersetshire, the success of such a school has been 
quite phenomenal. Sexey’s Trade School, as it is called, owes 
its inception to Mr. Henry Hebhouse, M.P., and was founded 
a few years ago out of the old endowments of Sexey’s Hospital 
under a scheme of the Charity Commissioners, with aid from 
the Somerset County Council. Recently I had an opportunity 
of seeing the school, and could not sufficiently admire the excel- 
lence of what is done there. The buildings consist of a master’s 
house, large schoolroom and lecture-rooms, well-equipped 
physics and chemical laboratories, wood and metal workshops, 
gymnasium, &c., with about two and a half acres of garden and 
playground attached. Besides instruction in the ordinary 
subjects of a higher primary or secondary school, the boys in 
the upper division (Classes II. to V.) are taught magnetism, 
electricity, chemistry, mechanics, manual work in cardboard, 
wood and metal, mensuration, French, botany and bookkeeping, 
and the instruction in technical subjects is throughout of a 
practical nature, being given in the garden, field, and work- 
shops, as well as in the class-room. Outdoor lessons are given 
in land measuring. Visits are occasionally paid to farms in 
the neighbourhood to inspect the stock, implements, buildings 
and crops. Botanical walks are taken at intervals in order to 
study plants in their natural habits, and the boys are encouraged 
to make collections of botanical and other specimens. 
Since 1896 the school has been organised as a School of 
Science, and through the courtesy of the headmaster, Mr. 
Knight, I am able to place the following details before your 
readers. The fees for tuition are 4/. and for boarding 20/. per 
annum. The school has been accepted by the Somerset and 
Wilts County Councils as one of those at which junior ana 
intermediate county scholars may attend. There are 103 
boys at the school, of whom 25 are the sons of farmers, 20 of 
artizans, and 32 of small tradesmen. Of those who have left 
the school 34 have taken to farming. as an occupation. From 
the forty-fifth Report of the Science and Art Department it 
appears that in 1897 the school presented 63 pupils for examin- 
ation. The grant earned was 384/., being an average of 6/. 25. 
per head. The High School at Middlesbrough stood next on 
the list with an average of 5/. 13s. per head, and the general 
“average for the 143 organised Science Schools in Great Britain 
was 3/. 9s. 6d. Such an experience as this ought to be of the 
greatest encouragement to those who are really anxious for the 
improvement of rural education, and the facts cannot be too 
widely known. This school differs from the one at Bigods in 
that it is only for boys; but a school is now being erected in 
the immediate neighbourhood to provide a modern education 
for girls, corresponding as far as possible with that provided for 
the boys. Joun C, MEpp. 
Stratton, near Cirencester, October 15. 
THE good work being done at Sexey’s Trade School is of 
course well known to all who have interested themselves in 
rural education. Readers of NATURE will no doubt be glad 
to have Mr. Medd’s independent testimony, and more par- 
ticularly the detailed statement of figures concerning grants and 
fees. At the present time, when the subject of rural education 
is so very much before the public, it would, however, be of the 
greatest assistance to those who are engaged in carrying on 
this work if Mr. Medd could supply more detailed information 
concerning the aid which the County Council has given and 
how this assistance has been rendered ; whether in the form of 
grants for building and equipment or for maintenance of staff, 
or both, Also what proportion of the initial cost of foundation 
as a School of Science was contributed hy the Somersetshire 
County Council? In the present state of rural education one 
cannot help feeling that the whole future success of these 
schools is very largely dependent on the constitution of the 
Technical Instruction Committees of the County Councils— 
especially in those cases where the County Council has become 
recognised as the central authority. Any information, therefore, 
that can be given on these administrative points, either with 
respect to Sexey’s or any similarly constituted school, would be 
most opportune. In the case of our school at Bigods, the 
initial cost of foundation and conversion into a School of 
Science has been mainly borne by Lady Warwick. The Essex 
County Council, as regards maintenance of staff, have put us 
on the same footing as the endowed schools in the county by 
granting 100/. annually. R. MELDOLA. 
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