Fesruary 18, 1897 | 
NATURE 377 
the coral platform which extends from them, up to and under 
the hurricane beach. This breccia was probably formed and 
cemented together when the reef stood at least 4 feet lower 
than at present, and was produced by the breakers driving 
fragments of corals from the seaward edge of the reef 
into the lagoon, as they are now doing over the isthmuses, 
submerged at high tide, which connect the several islets of the 
atoll together. 
If it should prove true, as I do not doubt, that one of the 
latest episodes in the history of the reef has been an elevation of, 
say, 4 feet, then in the immediately antecedent stage, the reef 
must have been a wash, or, perhaps, wholly submerged, and the 
present terrestrial fauna and flora mnst have reached it subse- 
quent to its elevation, as sea drift, or have been introduced by 
human agency. 
In conclusion, I would add that to myself the soundings 
obtained by Captain Field appear to support Darwin’s theory of 
coral atolls ; there remains, however, one very important branch 
of the subject which stands in need of renewed investigation, 
and this is the bathymetrical limit to coral life. Not till I had 
obtained a close acquaintance with the difficulties of dredging 
on the steep side of an atoll did I recognise on how frail a basis 
our accepted conclusions rest. It is a task difficult enough to 
get up corals from the lagoon in comparatively shallow water ; 
from the sides of the reef it is well-nigh impossible. To obtain 
dead corals from great depths proves little ; living corals are 
generally found with dead associates, and the latter are the 
more readily detached and brought to the surface. The weight 
of the evidence we already possess is admittedly in favour 
of a comparatively shallow bathymetrical limit, but much re- 
mains to be done before we can speak of any limit as definitely 
ascertained. 
THE INSTITUTION OF MECHANICAL 
ENGINEERS. 
ON Thursday and Friday, the 4th and 5th inst., the annual 
general meeting of the Institution of Mechanical Engineers 
was held in the theatre of the Institution of Civil Engineers, in 
Great George Street. The President (Mr. E. Windsor Richards) 
occupied the chair. The Secretary read the report of the 
Council, from which it appeared that the Institution continues 
to grow in numbers and to accumulate capital, it having an 
income of over 7000/. a year, and an expenditure of about 
5000/., the accumulated excess of receipts over expenditure 
being now over 46,009/. The Institution will shortly have a 
house of its own. Hitherto its offices have been a suite of 
rooms on the ground-floor of one of the buildings in Vic- 
toria Street, Westminster, a rent of 710/. being paid. The 
new building will be situated at the Storey’s Gate to St. 
James’s Park—that is to say, just at the bottom of Great George 
Street. The plans, which were exhibited at the meeting, show 
a handsome building, and as the front looks right on to the 
Park, the Mechanical Engineers will be very pleasantly housed. 
There will be a large lecture theatre, so that the Institution 
will no longer have to depend on the hospitality of the parent 
engineering Institution for a place to hold its meetings. Al- 
though this will naturally be a convenience, it will be with 
regret that the pleasant association between the two Institutions 
of host and guest will be severed. In looking at the new 
building of the Institution of Civil Engineers and the house of 
the Mechanical Engineers, now springing into existence only a 
few yards off, one cannot but think with regret what might have 
been done had the various Institutions devoted to engineering 
interests joined forces, and built a really commanding building, 
worthy, at the same time, of being a public monument to applied 
mechanical science. The Institutions of Civil Engineers, Mechan- 
ical Engineers, Naval Architects, Iron and Steel, and Electrical 
Engineers are all prosperous societies. Of course the Civil 
Engineers and Mechanical Engineers overshadow the others in 
wealth and influence, but they would have lost nothing by 
joining forces, for the accommodation afforded in the building 
could have been appropriated according to the amount con- 
tributed. There were naturally some difficulties in the way, 
but these could have been overcome. However, the chance of 
Great Britain, the birthplace of steam engineering, having a 
worthy home of engineering science is now past, and we can 
only look with appreciative interest on the efforts of the different 
NO. 1425, VOL. 55] 
societies to house themselves independently, but in a relatively 
modest fashion. The new building of the Mechanical Engineers 
will be finished in eighteen months. It has been kept back 
by difficulties with the London County Council. 
There were three papers set down for reading at the meeting. 
They were :-— 
(1) Fourth Report to the Alloys Research Committee. By 
Prof. W. C. Roberts-Austen. 
(2) Partially immersed Screw Propellers for Canal Boats, and 
the Influence of Section of Waterway. By Henry Barcroft. 
(3) Mechanical Propulsion on Canals. By Leslie S. Robinson. 
The Report to the Alloys Research Committee alone calls for 
any extended notice. 
Mr. Barcroft’s paper was read; and it had, however, the 
good effect of calling forth from Mr. S. W. Barnaby a very 
clear exposition of some points in connection with screw 
propulsion ; and also a speech from Mr. Thornycroft, which, 
together, will serve to put the matter in a true light in the 
Proceedings. 
The report of Prof. Roberts-Austen gave, firstly, some general 
considerations respecting the present position of the research ; 
secondly, it dealt with the copper zinc alloys, known as the 
brasses ; and thirdly, with certain relations between the fusi- 
bility and strength of alloys; and this involved considerations as 
to the constitution of alloys generally. An account was also 
given of an experimental investigation which was undertaken 
with a view to measure the molecular mobility of solid and 
molten metals, known as diffusion. 
In the series of researches, of which a part was described in 
the paper, the author had attempted to find how far the properties 
of metallic masses are dependent on atomic movement and 
molecular grouping. This part of the paper contains so striking 
a lesson on the value of scientific investigation of problems of 
a constructive or industrial nature, that we will quote Prof. 
Roberts-Austen’s introductory passage to this section in full. It 
ought to be unnecessary to do so, but the self-called ‘‘ practical 
man ”—who is really the most short-sighted and unpractical man 
in existence—has been so much in evidence of late, and has 
received so much support from a section of the technical press, 
that a corrective may well be administered. 
Prof. Roberts-Austen, referring to the course followed in the 
report, says :— 
““The mechanical properties of alloys of definite series of 
metals have assumed less prominence than the principles 
which affect alloys generally; and the result has been 
that, although the course adopted hardly needs justification, the 
practical bearing of the investigation may have seemed to be 
somewhat remote. The devotion of years of labour, for instance, 
to tracing the relations of alloys to saline solutions, would appear 
at first sight to be of less practical importance than determining 
the mechanical properties of alloys by the aid of testing machines. 
Establishing the analogy between alloys and saline solutions 
has, however, been eminently fruitful in practical results ; for it 
has enabled the mechanical properties of alloys to be explained, 
and even to be predicted. It has been easy to show that the 
property ofliquation possessed by saline solutions while freezing 
—which consists in rejecting a certain quantity, often very 
minute, of a fluid portion of the mass, and distributing or 
relegating it to a definite position in relation either to the mass 
as a whole, or to the individual crystals—is now recognised as 
being of fundamental importance in determining the mechanical 
properties of varieties of iron and steel and of alloys generally. 
This subject of liquation will always be identified with the work 
of the Alloys Research Committee, and its history is interesting. 
Its origin is French (Levol, Avnales de Chimie et de Physique, 
vol. xxxvi., 1852, p. 1933 vol. xxxix., 1853, p. 163); but much 
experimental work in this connection was published more than 
twenty years ago in a paper of my own (Proceedings of the Royal 
Society, vol. xxiii., 1874-5, p. 481) ; and the present Report will 
contain references to the latest phases of the inquiry, which may 
also be claimed as the outcome of the labours of this Committee. 
Attacking the problem of the constitution of alloys from the 
atomic point of view has, moreover, been fruitful in results ; for 
it has enabled the influence exercised by the relative atomic 
volumes of the alloyed metals upon the mechanical properties of 
the mass of metal to be clearly revealed.” 
The original problem proposed for consideration of the Alloys 
Research Committee was, ‘‘ Are the mechanical properties of 
metals and alloys connected with their atomic volumes?” This 
