188 ALQUIST GEARING FOR SHIP PROPULSION. 
which we can gain by diminishing the diameter of Pinion A and lengthening it must be 
exceedingly small since the peripheral speed varies as the pinion diameter and the linear tor- 
sional yield at the pitch line varies inversely as the third power of the diameter and directly 
as the length. Indeed, examining Fig. 9, one is struck by the small number of teeth which 
cross a longitudinal line on each spiral of Gear A—only about seven. So that the great 
advantage to be gained from a long pinion of small diameter and with fine pitch of teeth 
does not seem to have been followed up in practice. This also, as stated above, is not borne 
out by Fig. 5. If Mr. Emmet had given us the speeds, diameters, lengths, and tooth pitches 
for a reduction gear of a given power, we could have told exactly what some of his state- 
ments mean and what power constants he used. But he left us in the dark. 
6. In all reduction gears the weight of the gear wheel is a very large proportion of the 
total weight, although usually it is a hollow structure. But in the Alquist gear it is nearly 
solid. This must so greatly increase the total weight of the reduction gear that it will 
become forbidding for destroyers and other warships where weight is so important. This 
is further emphasized if the small and long pinion is not used, necessitating an increase of 
the Gears A and B. 
7. It is of great importance in ship propulsion that the engineer should have at least 
two strings to his bow. In the form of the Alquist gear I have been considering, which has 
been installed on some ships, there is only one turbine driving one pinion. If anything goes 
wrong with either of these in a single-screw ship, the engineer is helpless. I greatly prefer, 
both for safety and economy, a divided turbine driving two pinions.. 
Mr. A. C. Hotzaprre.t, Member (Communicated) :—I consider that the discussion on 
gearing for marine turbines will not be complete without some reference to the hydraulic gear- 
ing invented by Professor Fottinger. This gearing came out in 1910 when Professor Fottinger 
read a paper describing it before the German Institution in Berlin. It consists of the cen- 
trifugal pump delivering water to a water turbine, and was in the first place fitted to a small 
tugboat built by the Vulcan Company of this city, for home purposes. 
Having at that time the intention to build a seagoing vessel driven by gas power de- 
rived from a suction gas plant, and being unable to obtain a reversible gas engine, I decided 
to adopt the Fottinger transformer not only for the purpose of reversing but also for reduc- 
ing the revolutions of the gas engine, which were 480 per minute, to 120 on the propeller 
shaft. The transformer in question was the first commercial unit of the sort manufactured 
by the Vulcan Company and answered its purpose perfectly. There was a loss of about 16 
per cent of power. 
A number of larger transformers were subsequently built for the German Navy and 
mercantile marine, and when I last heard from my friends on the subject, there were trans- 
formers of more than 150,000 horse-power under construction by the Vulcan Company. 
The British patents were acquired by the firm of Beardmore, of Dalmuir, near Glasgow, but 
they did not at once start the construction. I have, however, recently received news that 
they have now started to built Fottinger transformers. 
In 1912 I had discussions with Sir Charles Parsons about the Fottinger transformer. 
At that time, it was suggested by Professor Fottinger that the Parsons gearing would not be 
applicable to very large units, as, for instance, a battle cruiser, and Sir Charles seemed to 
give serious consideration to this suggestion at that time and was actually in negotiation for 
acquiring the Fottinger patent rights, presumably for the purpose of supplying this trans- 
