NoveMBER 12, 1896] 
NA TLORE 
45 
Mr. Longridge said that the observed result of the steam 
being not cloudy, all the moisture being concentrated in a film 
on the walls of the cylinder, would materially affect the condi- 
tions involved in passing steam from a jacket to a cylinder, as 
the steam would not carry condensed water with it. Mr. 
Halpin questioned the fact of there being no additional resist- 
ance to the transmission of heat owing to multiplication of 
surfaces. The authors’ statements on this point are opposed to 
the opinions held by many engineers ; and even if they are right | 
in regard to areas absolutely in metallic contact—like floating 
surface plates—those perfect conditions are not present in 
practical engineering work. 
The second evening of the meeting was devoted entirely to 
Mr. Longridge’s paper ; a most useful contribution to the 7razs- 
actions of the Institution, although not very easy to follow 
without the aid of illustrations. The paper dealt with 1000 
break-downs of factory engines which had come before the 
author's notice. These Mr. Longridge had analysed and classified 
in order to show which parts of the engines gave way first, and 
as far as possible the causes of failure were stated. In some 
instances the author suggested steps which should be taken to 
avoid similar mischances in the future. The thousand break- 
downs were divided into 23 groups, and these were again sub- 
divided into divisions. Thus there were 213 accidents due to 
the giving way of ‘‘valves and valve gear,” and in these were 
included the giving way of 46 valve spindles, 24 eccentric straps, 
3 rocking shafts and levers, 21 nuts, cotters, and pins, 18 
eccentric rods, 17 slide valves, besides other parts of valve gear 
in lesser proportions. It is notable, considering how much 
dread some millowners have of the “clattering Corliss gear,” 
that only seven accidents are chronicled against this method of 
steam distribution, especially when one remembers how largely 
it is now used in Mr. Longridge’s district of Lancashire. Valve 
spindles break when screwed, and this fact leads the author very 
properly to exclaim against the use of V-threads. Gas threads, 
he says, are better ; and round threads best of all. The sharp 
V-thread is like the commencement of a tear. Next to valve 
gear “‘spur wheels” come on the list, with a total of 124 
accidents. Mr. Longridge only includes wheels on the crank 
shaft ; if he had taken second-motion shafts, the total would have 
been incomparably greater. Back-lash is the most fruitful source 
of mishap with toothed wheels, and a most fruitful source of 
back-lash is placing spur gearing and rope or belt pulleys on 
the same shaft, when the second motion shaft is apt to overrun 
the main shaft. Uniform load, a heavy fly-wheel, and slow 
speed of ropes, are points that need to be observed in such cases. 
Vibration is also a frequent cause of accident with spur gearing. 
Machine-moulded teeth are best, and it is desirable to carry the 
toothed quadrants on the arms of the fly-wheel rather than have 
teeth on its periphery. Air-pump motions are next ; they caused 
121 breakdowns. The chief heading in this division is ** weak- 
ness, wear and tear, or neglect” ; causes which speak for them- 
selves. 
Air-pump buckets and valves were responsible for eighty-eight 
out of the thousand accidents. These mishaps were mostly due 
to the giving way of parts, foot-valves being the chief delinquents. 
In reference to accidents through broken packing rings in 
buckets, the author said he would as soon have plain buckets, 
packing rings being ‘“‘expensive, dangerous, and entirely use- 
less,” One speaker, Mr. Saxon, who himself has had consider- 
able experience with mill engines in the same district, agreed with 
the author in regard to low lifts, but if a high lift were required, 
he considered packing necessary. ‘‘ Columns, entablatures, 
bedplates, and pedestals” accounted for eighty-six break-downs. 
The settlement of foundations is the most frequent cause in this 
division, and the author warns engineers against setting-up 
holding-down bolts in columns when the masonry settles, as this 
naturally brings undue stresses upon the structure of the 
engine. The difficulty is that engineers very often do not 
recognise that the masonry foundations are settling when a 
column becomes loose on its seating. The chief cause of the 
decay of foundations appears to be the deterioration of stones, 
and cement or mortar by oil getting to them. One speaker 
during the discussion—Mr. Rounthwaite, a marine engineer— 
asked why the designers of mill engines were so fond of brick- 
work, and suggested that it would be preferable if very deep 
_ cast-iron bedplates were used so as to reduce the masonry 
required. The author said that the gradual spread of the 
vertical or inverted type of engine facilitated the use of deeper 
metal bedplates. The horizontal engine had held its position 
NO. 1411, VOL. 55] 
so firmly because it gavea long stroke, but with the speeding up 
of mill machinery, characteristic of modern practice, a higher 
rate of revolutions was required, and this made _ shorter 
stroke engines preferable, so that the vertical type was 
gaining ground. Main shafts were the cause of forty-nine 
accidents, some of them the most interesting of the Series. 
By far the greater number of shafts that broke down’ gave 
way through wear and tear. One veteran made 176 million 
revolutions before being taken out, owing to a mysterious grooving 
under an eccentric sheave. A Whitworth fluid-compressed 
steel shaft gave poor results, running only 614 revolutions, 
and giving way under the low stress of 4600 lbs. per square 
inch. This single case, however, will not be sufficient to 
destroy the high reputation of Whitworth shafts. Connecting 
rods, of which forty-one gave way, break almost invariably 
in the connections, gibs cotters, open-ended straps or bolts 
giving way ; one instance of a body failure, through an imperfect 
weld, alone being recorded, although there were six failures of 
forked ends. Cylinders and valve chests, with which there 
were thirty-five accidents, mostly break on flat surfaces, covers, 
or doors; the presence of water being the chief cause. 
Parallel motions account for thirty-five breakages, mostly in eye 
shafts. Governors supplied twenty-eight accidents to the list, 
and piston-rods twenty-seven ; cotter-holes being again the 
weak point. The author very rightly warns designers against 
abrupt changes of section in piston-rods, for though the average 
draughtsman appears to be quite alive to this evil in regard to 
castings, yet he often appears to think it produces no bad effect 
where the effects of unequal cooling are not to be anticipated. 
Piston-rod crop-heads afford twenty-seven examples of break- 
downs, mostly from “‘ wear and tear” ; the giving way of pistons 
supplies an equal number of mishaps, whilst the breaking of links 
contributes twenty-one accidents towards the total. 
Nineteen break-downs of fly-wheels are recorded, the chief 
cause being internal stress—due presumably to ill-proportioned 
castings—whilst eight bosses were cracked, five by driving keys 
too hard. The author made some pertinent remarks on the 
question of keying fly-wheels on to shafts, describing the 
Lancashire method of ‘‘staking,” which is the best plan for 
giving a true running and rigidly secured wheel without strain- 
ing the boss. Mr. Holroyd Smith, in the discussion, sketched 
an improved form of key which appeared to be designed on 
sound principles. Air-pumps and condensers gave way thirteen 
times, gudgeons in beams twelve times, and cranks twelve 
times. Of the latter eleven were of cast-iron, so there is not 
much need to comment upon them. Eleven crank-pins broke ; 
in one case a Whitworth steel pin gave way through the skin 
being injured by shrinking in the crark web. The tear being 
started, failure was but the result of time. There were only 
six instances of broken engine beams. One the author attributes 
simply to fatigue. The engine was made in 1847 and worked 
until 1892, when some fine cracks were noticed near the middle 
of the beam, which was of cast-iron. These cracks developed, 
extended, and joined up, so that the beam was condemned. 
Prof. Hudson Beare joined issue with the author on the pro- 
priety of attributing the failure of this beam to fatigue. He 
said that once the original crack was set up, the beam was ina 
less advantageous position to bear the load put upon it, so that 
the crack would be further developed until it finally succumbed. 
The remaining causes of accident were failures of slide-bars 
five, and of ropes three; whilst an ‘‘entire smash,” no cause 
ascertained, completes the roll of a thousand break-downs. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE. 
CAMBRIDGE.—The following science teachers in the Uni- 
versity were, on November 7, elected members of the Council 
of the Senate: Alex Hill, M.D., Master of Downing, and 
University Lecturer in Advanced Anatomy ; R. T. Glazebrook, 
F.R.S., Assistant Director of the Cavendish Laboratory ; and 
A. E. Shipley, University Lecturer in the Morphology of Verte- 
brates, and Secretary of the Museums Syndicate. Dr. R. C. 
Jebb, M.P., and Dr. J. N. Keynes, Secretary of the Local 
Examinations Syndicate, were also among the successful 
candidates. 
The Professorship of Surgery has been again suspended until 
the first day of next term, to give time for the further considera- 
tion’ of the stipend and conditions of tenure. It appears 
