ist 
, 
April 20, 1882 | 
NATURE 
587 
service rendered to the vessel, and not the freight-earning 
power as the basis of assessment. Mr. White differs, 
however, from Mr. Rothery in the mode in which the 
space occupied by the vessel should be measured. He 
considers that for all practical purposes this space is equal 
to the parallelopipedon formed by the extreme length, 
extreme breadth, and the mean draught, and consequently 
thinks that “ parallelopipedon tonnage,” as it is called, 
has much to recommend it. The possibility of berthing 
other vessels at the same dock or wharf is not sensibly 
altered by the under-water shape, consequently the above 
seems a fair measure of service rendered. 
Mr. White does not consider that the above proposal 
would lead to the adoption of a box-shaped type of vessel. 
He thinks that the cost of propulsion of a steamer would 
effectually check any such tendency. 
Mr. White concludes his most able paper by the fol- 
lowing piece of advice, which we trust may be taken to 
heart by whatever government finally undertakes to 
revise the tonnage laws. 
“Tn conclusion, I would venture one remark respecting 
the course of procedure which promises to give the best 
results, if a revision of the tonnage law is decided upon. 
Valuable as the labours of committees and commissions 
may be in testing the feeling of those interested in ship- 
ping, and putting on record the opinions of competent 
authorities who view the subject from different stand- 
points, it does not appear that a satisfactory revision can 
be looked for in this direction. The precedent to be 
found in the preparation of the law of 1854 seems to be 
a good one. Following after the work of the com- 
missions came the careful, extensive, and laborious in- 
quiry of Moorsom, a scientific expert, having a thorough 
acquaintance with the subject, and placed in direct com- 
munication with the shipping community. If the long- 
talked-of Central Council or Advisory Board should be 
constituted to deal with matters relating to the mercantile 
marine, and if it should be assisted by a competent scien- 
tific staff of naval architects, we may hope that, among 
other much-needed action, will be included the revision 
of the tonnage laws in a sense that will give more general 
satisfaction than could otherwise be obtained.” 
THE NAVAL AND MARINE ENGINEERING 
EXHIBITION 
HE Exhibition which Mr. Samson Barnett, jun., 
has opened at the Agricultural Hall, and which 
closes to-day, contains a very large number of objects 
connected directly and indirectly, and sometimes even 
totally disconnected with naval purposes. The col- 
lection is by no means totally devoid of novelties 
and of objects of considerable scientific interest. The 
Exhibition contains numerous models of recently-built 
war and merchant ships, a few small marine engines 
and boilers, and portions of large-size marine boilers, 
together with fittings of engines and boilers in great 
variety. There are also several specimens of steam 
steering gear, ships’ telegraphs, steam capstans, cranes, 
and machinery generally for loading and unloading 
vessels, boat-lowering apparatus, life-saving appliances, 
dredging gear, and refrigerating appliances. Naval 
artillery was not well represented, but Messrs. Hotchkins 
and Co. exhibited some fine specimens of their beautiful 
revolving cannon, which have been adopted in the navies 
of several foreign governments, notably in those of 
France, Germany, Russia, and Italy. 
The ships’ models are as a rule very deficient in 
interest,,in spite of the fact that they represent many 
of the most famous of modern vessels, such as the Devas- 
tation and Polyphemus, among men-of-war, and the 
Servia, the City of Rome, and the Ravenna amongst 
passenger steamers; for they were mostly half models of 
the outsides of the vessels, which, though they give a very 
good idea of the exterior form, afford no information as 
to the construction, the interior arrangements, or the 
engines and boilers. This is somewhat disappointing 
when we remember what strides have been made in 
recent years in the construction of iron ships. 
In the Department of Marine Engines and Boilers there 
was aremarkable absence of models, or even of drawings 
of the very fine engines with which our first-class war 
and merchant steamers are now fitted. By far the most 
important objects exhibited in this section were the mag- 
nificent flanged front plates of boilers, one of these being 
fifteen feet in diameter, and made in a single piece, with 
three flanged openings for furnaces, from a single 3-ton 
ingot of Siemens’ steel. The same firm also exhibited 
several specimens of Fox’s corrugated furnaces, an in- 
vention which has conferred the greatest benefits on the 
cause of steam navigation, by rendering possible the use 
of the very high boiler-pressures which are so essential 
to economy of fuel. Mr. David Joy also showed a model 
of his own celebrated valve-gear, which has given such 
excellent results with locomotives at Crewe, and which 
will doubtless soon become favourably known to marine 
engineers. This valve-gear is probably the most serious 
competitor to the old link-motion driven by eccentrics, 
first adopted by Stephenson for locomotives, and which 
has remained in pretty general use up to the present 
time. Mr. Joy’s motion, besides being simpler, effects a 
better distribution of the steam, in many respects, than 
the link-motion. 
Amongst the most interesting features of the Exhibi- 
tion were the refrigerating machines. Of these there 
were four, exhibited by Messrs. Bell-Coleman, Messrs. T. 
Pigott and Co., the Haslam Foundry and Engineering 
Company, and Messrs. J. and E. Hall. As we have so 
recently described the principle of action of these 
machines, it will not now be necessary to go into de- 
tails. It may, however, be mentioned that they are at the 
present moment being used by the Peninsular and Oriental, 
the Cunard and the Orient Steam-ship Companies, and 
also by the London and St. Katharine Dock Company, 
and the Orange Slaughtering Company. The successful 
application of mechanical refrigeration to the preservation 
of fresh meat and other provisions, is a subject of such 
immense importance, that we are not surprised at the 
great interest excited by these machines. 
Amongst the miscellaneous exhibits we can specially 
mention the numerous collapsible and other life-boats, 
and the boat-lowering apparatus, some of which are 
really admirable. Also the wire-rope rigging, and the 
stout wire torpedo nets, exhibited by Messrs. Bullivant 
and others. 
It seems a pity, considering the great amount of 
interest which has been excited by this Exhibition, that 
it should only remain open for ten days. 
TOTAL ECLIPSE OF MAY 17 
\ E have given from time to time, in the Astronomical 
Column, particulars of the approaching total 
eclipse, pointing out that it is visible at a point on the 
Nile, in lat. 26° 32’ N. Weare glad to be able to state, 
that an expedition left this country yesterday with the 
view of obtaining photographic and spectroscopic obser- 
vations. The expedition has been organised by the 
Science and Art Department and the Royal Society 
combined, on the recommendation of the Solar Physics 
Committee. 
The expedition sails to Suez in the Peninsular and 
Oriental steamship Aazsar-2-Hind, and a good idea of 
the local arrangements made will be gathered from the 
accompanying article, which we reprint from the Dazly 
News of yesterday :— 
May 17, 7 am., sun eclipsed, visible at Greenwich. 
Thus runs the records in our pocket-books. So short, 
