OcTOBER 23, 1902] 
NATURE 
643 
being largely composed of lowland, calcicole, and aquatic or 
paludal species ; the marginal of calcifuge, upland and dry-soil 
plants. Well-marked northern and southern, eastern and 
western groups also exist, the boundaries between them consist- 
ing of lines running not exactly east and west or north and 
south, but rather north-north-eastward from Cork to London- 
derry and east-north-eastward from Galway Bay to Dundalk 
Bay. For these six types of distribution the author proposes 
the names Central, Marginal, Ultonian, Mumonian, Lagenian, 
Connacian, the last four being taken from the old names of the 
four provinces of Ireland, in each of which one of the groups 
attains its maximum. The characters of each plant-group, and 
its relations to the climatological and physiographic features of 
the country, were pointed out. 
Two papers of economic importance were read, Prof. John- 
ston showed the distribution of peat bogs in Ireland by means 
of a new map prepared by the Intelligence and Statistical Branch 
of the Irish Agricultural and Technical Instruction Department. 
They cover 1861 square miles, chiefly in counties Donegal, 
Mayo and Galway, and have an average depth of 25 feet. An 
account was given of the character of the different layers of a 
bog as seen in a vertical section, and an explanation suggested 
of the origin of a bog-slide. Specimens of the bog-flora, of the 
different kinds of peat and of the economic products derivable 
from turf or peat, lent from the botanical collections of the 
National Museum in Dublin, were exhibited. The second paper, 
by. Mr. R. B. Buckley, on colonisation and irrigation in Uganda 
and the British East African Protectorate, began with a clear 
picture of the existing physical and economic conditions of these 
dependencies, and enunciated comprehensive and judicious views 
as to their development in the future. The question of irrigation 
was exhaustively treated, and the author concluded that the 
prospects of great transformations taking place through its aid 
are not very hopeful. IS [tsk 
ENGINEERING AT THE BRITISH 
ASSOCIATION. 
ON’ Thursday, September 11, after the president’s address, 
a paper by Mr. H. A. Humphrey on recent progress in 
large gas engines was read. This paper, which was illustrated 
by lantern slides, gave an account of the extraordinary develop- 
ment of large gas engines which has taken place during the 
past few years, and which has, as the author said, had but few 
parallels in the history of engineering enterprise. In the Paris 
Exhibition of 1900, a 600 h.p. Cockerill gas engine was, from its 
size, the object of much interest. The same makers are now 
building engines of 2500 h.p., and they are prepared to under- 
take one to develop 5000 h.p. In this country it is only as 
recently as 1900 that engines above 400 h.p. have been made, 
the first two being constructed for Messrs. Brunner, Mond and 
Co.’s works at Winnington, yet when the paper was written 
(August) the two chief manufactories in Great Britain had under 
contract or had already delivered no less than fifty-one gas 
engines ranging in size between 200 and 1000 h.p. But it is 
on the Continent and in America that the most remarkable 
advance has been made. The author gave in a very complete 
table particulars of all engines of more than 200 h.p. capacity 
which have been built abroad or are under construction, the 
total amounting to 327 engines, developing 181,605 h.p. Slides 
shown by the author illustrated the various uses to which these 
large gas engines have been put so far, such as dynamo driving, 
air compression for blast-furnace work, and other similar uses. 
Perhaps the most interesting detail in connection with this in- 
crease in the size of gas engines has been the use of blast-furnace 
gas for working them: The author in the latter part of his paper 
explained in some detail the improvements in construction and 
governing which have made these large engines possible, in 
particular the changes which have been necessary in the old 
“‘hit and miss” governor mechanism, where, as in dynamo 
driving, perfect uniformity of speed is necessary. As several 
large engineering firms in this country have now acquired the 
rights for manufacturing some of the most successful foreign 
types of these engines, there is little doubt that we are on the 
eve of important developments in this country in the gas-engine 
industry, especially in the utilisation of producer and of blast- 
furnace gases. 
In the afternoon of September 11, the Section made a special 
visit to the harbour works, under the guidance of the engineers 
NO. 1721, VOL. 66] 
to the Belfast Harbour Commissioners, in order that members 
might see for themselves some of the remarkable developments 
which have taken place in Belfast Harbour and have been brought 
about by constant increase in the size of ocean steamships. 
On Friday, September 12, the first ‘paper was a brief com- 
munication by the Hon. C. A. Parsons on steam turbines, 
in which figures were given to show the rapid increase in the 
use of the compound turbine since 1884. Up to 1890, though a 
number of compound turbines had already been constructed for 
driving dynamos, the largest size had not exceeded 120 h.p., 
the total h.p. at that date being 5000; by 1896 the total h.p. 
had increased to 40,000 and the largest individual plant to 
600 h.p., and now the largest unit has increased to 3,000 h p. 
and the aggregate h.p. sold in Great Britain to 200,000, On 
the Continent, also, their use has been rapidly extending, and 
the total aggregate of horse-power at home and abroad for driving 
dynamos up to the present time is not far short of 300,000, As 
a proof of the remarkable economy obtained in the very large 
machines, the author stated that a steam consumption of 
17°3lb. per kilowatt hour had been recorded during a test of 
a 1000 kilowatt continuous-current machine belonging to the 
Newcastle and District Electric Light Company ; this would 
be equivalent to about 1o’2lb. of steam per i.h.p. hour, 
a very remarkable figure, and he anticipates still greater 
economy in the future in turbines of large size when using 
superheated steam. Many engineers had feared that these 
machines would fall off notably in their economy after they 
had been running for some time, but the author stated that care- 
ful tests had now been made with several plants to determine 
the steam consumption after the machinery had been in use 
for several years, and no appreciable increase had been found. 
The second half of the paper was devoted to an account of the 
application of the steam turbine to marine work ; seven vessels 
have so far been fitted with turbine engines, including the two 
unfortunate destroyers—the Cobra and the Vzfer—and the two 
well-known Clyde passenger boats—the Azwzg Edward ani the 
Queen Alexandra. In addition to these, a third-class cruiser, the 
Amethyst, would shortly be completed, and orders have recently 
been placed on the Clyde with Messrs. Denny Bros. for the 
construction of two cross-channel boats which are to have 
turbine engines of about 8000 h.p. ; this means a total of about 
3,000 h.p. in use or in construction. Mr. Parsons stated that 
if the coal consumption of the Duchess of Hamilton (fitted with 
ordinary reciprocating compound engines) was compared with 
that of the Avug Edward, and if various allowances for the 
difference in speed of the two boats and for various other factors 
were made, then the turbine boat showed a saving of 20 per 
cent. ; he again, as at the Dover meeting, prophesied the 
eventual use of turbine engines for Atlantic liners, cruisers and 
battleships. In his reply to a brief discussion, in which several 
points were raised with regard to the use of superheated steam 
in the turbines, the author stated that he estimated a gain of 
efficiency due to superheating of about 1 per cent. for every 
10° of superheat. 
The next matter dealt with by the Section was the report of 
the Committee on the Resistance of Road Vehicles to Traction, 
the first eleven sections of which were devoted to a complete 
vésumé of the experimental work which has already been carried 
out on this subject, and to a summary of the opinions which 
have so far been expressed (based on these experiments) of the 
effects on traction on the level of the three independent elements 
of road resistance, namely, axial friction, rolling resistance and 
grade resistance. The last two sections of the report were 
devoted to a brief description of the special apparatus which 
has been designed and made by the Committee ; the first series 
of experiments undertaken will be confined to measurements 
of the resistance of single wheels. The tractive force will be 
transmitted through a system of levers to a small ram which 
presses upon a rubber diaphragm enclosing a space filled with 
water or other liquid ; the pressure exerted by the levers on the 
ram will vary with the tractive force, and the consequent varying 
fluid pressure will be registered by a recording pressure gauge 
of the Bourdon tube type, and since the drum of the instrument 
carrying the recording paper will be rotated in strict accordance 
with the movements of the car, a diagram will be drawn giving 
the tractive force at all points on the journey. The instrument 
has been so designed that the leverage on the ram can be altered 
to ensure diagrams of a reasonable size even when the tractive 
force is very small, and a revolution counter will be used for 
obtaining independentiy the revolutions of the experimenta 
