470 
actual curvature a close approximation to this should occur, the 
echo of the sound thus emitted would travel along the platform 
and extend a short distance beyond it, and thus be distinctly 
audible to the beefeaters arranged along the platform, and to 
those who like myself were sitting close to it. 
When the Prince read his address, he stood very nearly in 
the south focus of the ellipse, a little the east side of it. In 
facing Her Majesty his voice was projected directly towards that 
portion of the panelled curve which should theoretically supply 
the parallel waves of sound to my side (the west) of the platform. 
‘hus the distinctness with which I heard the echo of his voice 
is explained, and also the absence of echo in those parts of the 
hall farther distant from its major axis. 
Her Majesty was near the focus, but not so near as the Prince 
of Wales. Santley was considerably to the west, and Madame 
Sherrington was on the east of the focus, but not so far removed 
as Santley. The quality and pitch of Madame Sherrington’s 
voice would of course assist in rendering the echo more distinct. 
The band and chorus being distributed between the focus and 
vertex of the ellipse, fulfilled their theoretical requirements by 
having no regular echo, nothing beyond an indefinable rumble. 
That the distinct echoes I heard came from the wooden lining 
was evident to the sense. I have often amused myself by ex- 
perimenting upon mountain echoes, and when there is no 
redoubling have usually been able to detect the direction of their 
issue, and to find the rock surface producing them. The echoes 
of the voices of the Prince of Wales, Her Majesty, and Madame 
Sherrington, were remarkably free from any degree of redoubling, 
and evidently came from the direction of the south wall. 
The remedy for this is obvious enough. This blank wall space 
must be covered with some kind of drapery, or broken up by 
ornament. Drapery will promote absorption of sound, an 
irregular’ ornamental surface will convert the regular reflection 
into scattering reflection, 
I listened very carefully for any indications of echo from the 
roof, but could detect none, either the velarium was quite effective, 
or the echo, formerly attributed to the roof, came from the walls, 
or my position prevented me from hearing the roof echo. As I was 
not present at the first experimental concert before the velarium 
was put up, I will not venture any opinion on these points. 
My apology for publishing these details is that the subject of 
the acoustics of this Hall is one of vast importance, both in 
reference to the Hall itself, and the intellectual progress of the 
inhabitants of all great cities. If large masses are to be taught 
orally, we must learn how to construct buildings in which the 
human voice may be audible to assembled thousands. The 
Royal Albert Hall presenting the grandest, and, I think, we 
may now say, the most successful experiment ever yet made in 
determining the possible limits of oral teaching, every contribution 
to a knowledge of its acoustic properties is of great value. I 
offer the above simply as such a contribution of observations 
made from one point—perhaps the most important point, and 
hope that it will be followed by other observations from other 
parts of the building. By combining these a correct knowledge 
of the whole subject may be obtained. 
W. Marriev WILLIAMS 
Gum Dammar 
In a valuable article in the current number of the ‘‘ Quarterly 
Journal of Microscopical Science” the Radcliffe Travelling 
Fellow alludes to the general favour with which Prof. Stricker 
and other eminent German workers, regard Gum Dammar as a 
substitute for Canada Balsam as a medium for the preservation 
and preparation of histological specimens. Mr. Mosely further 
points out an unfortunate mistranslation in the Sydenham Society's 
English edition of Stricker’s work, in which Dammar jirniss is 
translated Canada Balsam, and regrets that good Dammar firniss 
(Anglice dammar varnish) cannot be obtained in England, though 
the gum itself is sufficiently common. It so happens that I have 
made use of various home-made preparations of Dammar in 
preference to balsam for some time past. I have found that it 
not only isa substitute for the latter ‘‘torment to beginners,” 
but that it possesses many advantages over balsam, ¢.g. it is easier 
to use, sets more rapidly, and is above all clearer, more per- 
fectly transparent, and more dense. Perhaps many of your 
microscopical readers will be glad to learn that a very good 
‘*dammar varnish” is made and sent out ina suitable form by 
Mr. Walter White, of Monmouth, to whom I am indebted for 
my knowledge of some valuable formule for its preparation. 
Hull H. PocKLINGTON 
NATURE 

{ Agrel 13, 1871 

THE JRON AND STEEL INSTITUTE 
1% NATURE for March 30, we called attention to the 
annual meeting of the above society, which had just 
commenced in London. The new President, Mr. Henry 
Bessemer, delivered his opening address on the afternoon 
of Tuesday, when there was a large and influential attend- 
ance of the members from Scotland, South Wales, the 
North of England, South Staffordshire, Yorkshire, and 
other districts connected with the industries represented 
by this Institute. There were also several gentlemen 
present representing Continental and American works. 
Various matters of considerable practical importance 
were introduced to the notice of those present by Mr. 
Bessemer, and it is understood that the attentino of the 
Council will shortly be directed to carrying out, as far as 
possible, the suggestions contained in the address. Per- 
haps the most important subject mentioned was the pra- 
posal for a new series of tests to ascertain accurately the 
relative strengths ofironand steel. Many of the data upom 
which engineers and manufacturers have now to depend 
are comparatively old, and refer to classes of iron that are 
not made so extensively as they were at the time the expe- 
riments were instituted. New classes of iron have risen 
into importance during the last few years, and steel has 
become a very valuable article for engineering construc- 
tion, so much so that it is desirable the materials now 
available for use should be thoroughly tested, in order 
that their properties may be fully understood by engineers 
and ironmasters. The proceedings at the meeting on 
Wednesday and Thursday were of a varied and interest- 
ing character. The committee appointed to investigate 
the subject of distribution of iron ores in Great Britain, 
presented their preliminary report, in which they stated 
that they had received from gentlemen connected with 
the trade special communications upon the matter. They 
gave a résumé of the production of iron ore in the various 
districts, and in many cases they intimated that the 
mineral statistics published by the Mining Record Office 
did not accurately represent the quantity of material 
raised. Taking a general view of the production of iron 
ore in the United Kingdom, they remarked that attention 
is now being mainly directed to the development of those 
districts that yield the cheaper classes of ore, such as 
Northamptonshire, Lincolnshire, and Cleveland, and to 
those localities where deposits of haematite are obtainable. 
The great demand for the latter ores is stimulating research 
in every direction where there is a probability of this 
mineral being found, but the circumstances under which 
it was deposited are at present so imperfectly understood 
that it is impossible to estimate with any precision where 
these researches are likely to prove successful. The Com- 
mittee was re-appointed, and we understand that it is their 
intention to proceed with the preparation of a more 
thoroughly comprehensive report upon the subject of 
their investigations, and that this will be presented at an 
early meeting of the Institute. 
The Committee appointed to report upon the question 
of mechanical puddling stated that they had given con- 
siderable attention to the subject of their investigation. 
They had paid visits to the principal forges where furnaces 
for mechanical puddling were in operation, and they gave 
a detailed list of such works. With respect to the Con- 
tinent, they reported that Mr. Menelaus had kindly under- 
taken to obtain from France a set of the apparatus used 
at La Haynge, to put the same in operation at Dowlais, 
and to ask the Committee to see it at work in due course. 
Had it not been for the Continental war this machine 
would long ago have been at work, but it was detained in 
transit, and has not yet arrived in England. The Com- 
mittee intimated that they were making arrangements 
for obtaining the services of a practical engineer, and of 
a gentleman acquainted with puddling, to visit the differ- 
ent works, and thoroughly to investigate the merits of the 
