NOVEMBER 26, 1903] 
MAT LOILE: 
79 
EPREPRS LO) LHE EDITOR. 
[The Editor does not hold himself responsible for opinions 
expressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of Nature. 
No notice is taken of anonymous communications. ] 
Engineering Equipment of the Manchester School of 
Technology. 
THE report on engineering work at the British Association 
Meeting at Southport in your issue of October 29 contains 
certain criticisms with regard to the engineering equip- 
ment of the Manchester School of Technology.. The re- 
sponsibility for the character of this equipment rests 
ultimately upon me as the professional adviser of the 
Technical Instruction Committee, and I would therefore 
seek some space in your valued columns for making reply. 
The criticism takes two forms :—(1) that the laboratory 
equipment is unnecessarily complicated and beyond the 
capacity of the class of students the school is likely to 
obtain; and (2) that in any case, even if justifiable as to 
its nature, it was wrong to put in so much plant at once, 
but that part of it should have been held back until the 
growth of students showed a necessity for it. 
The reply to both is, that it was in the hope of attract- 
ing that very class of student the critic is so sure we are 
unlikely to secure that so extensive and elaborate a plant 
was installed. 
The great defect of technical education as hitherto con- 
ducted in this country has been its restriction to the teach- 
ing of elementary engineering science and to a few stock 
laboratory operations, such as breaking specimens in a test- 
ing machine, taking indicator diagrams from steam and 
gas engines, and making the simpler hydraulic experiments. 
This restriction was necessary, because the pupil, being a 
youth fresh from school, who had never seen the inside of 
an engineering workshop, and had to be taught everything 
from the commencement, could not be expected to advance 
very far in engineering knowledge. When he afterwards 
went into practical work, the knowledge acquired at the 
technical school being of no immediate use to him, he was 
no better off than if he had gone straight from school to 
the works, and his employer was not slow to notice this 
and draw the inference that the work of the technical school 
was practically of no value to the engineering industry. 
This is why the large majority of employers take so little 
interest in ‘*‘ technical education.”’ 
In Manchester, on the other hand, we have broken fresh 
ground, and are attempting to convince the engineering 
leaders that if they provide us with only one or two of the 
best young men out of each of their works, who have spent 
a few years in the workshop, and who know the elementary 
parts of geometry, algebra, trigonometry, and mechanics, 
We can, with two years of study and experimental work, 
turn out a product superior in every useful respect to even 
the much vaunted Charlottenburg diplomé, and of real and 
immediate monetary value to the profession. 
We propose to prove this by showing those leaders the 
practical utility and industrial value of the results of our 
research work, and also by returning to them their young 
men, not mere beginners without self-confidence (though 
stuffed with formula), but trustworthy observers, resourceful 
experimenters, and men of imagination, who are able to 
impart new ideas to those engaging them, and. to help 
them to work these ideas out in a practical way. 
Take, as an example, the experimental engine to which 
you refer as being a huge mistake. 
Take it for granted that a large percentage of the waste 
in steam engines is due to the defective design of valves. 
If we can show to some of these young designers of the 
future by experimental research upon this engine how these 
valves are defective, and in what direction to look for im- 
provement, we are surely aiming at a higher measure of 
utility than could be attained by demonstrations with any 
number of varieties of the market article, however modern. 
In regard to the remarks made about the equipment be- 
coming obsolete, the scope and object of the plant has again 
been entirely misunderstood. The laboratories are not in- 
tended to serve as museums of modern appliances which 
the student comes to examine, copy, and store his memory 
NO. 1778, VOL. 69 | 
with, but as a collection of machines typical of the various 
branches of mechanical engineering, specially fitted up for 
the purpose of studying the action of those working fluids 
and those moving mechanical elements which are common 
to all forms of prime movers and energy absorbers, past, 
present, and to come. 
With reference to the question of the size of the individual 
parts of the equipment, one of the things for which, in my 
opinion, local engineers must ever feel grateful to the Man- 
chester Technical Instruction Committee is the courage 
they showed in putting down plant on a true engineering 
scale. No practical experimental results worthy of attention 
could otherwise have been obtained. It could hardly be 
expected, for example, that an engineer, wishing to know 
the laws of the action of automatic drop valves for a design 
of large high-speed pump, should rest content to be guided 
by experiments made with a donkey-pump, however 
elaborate they might be. 
In concluding, may I give expression to my belief that 
the promise for the future of British engineering lies in 
practical experimental research, strenuously carried on 
either in the workshop- or the college-laboratory by men 
specially trained for the purpose, and that the sooner we 
get rid of the notion that teaching schoolboys some engineer- 
ing theory and the making of a few stock laboratory ex- 
periments constitutes the proper education for the engineer 
of to-day, the sooner we shall begin to recover from the 
reproach of having fallen behind the foreigner. 
Joun T. NIcoLson. 
On two Constants A, and A, in the Kinetic Theory 
of Gases. 
MAXwELLt has introduced two constants A, and A, in the 
kinetic theory of gases (Scientific Papers, vol. ii. p. 41), de- 
fined by the integrals 
where 
T j———=— vw}: 
U=5> \'cos 2¢ K (sin 9), 
K being the complete elliptic integral of the first kind with 
modulus sin @. These constants enter into the discussion of 
various properties of gases, on the assumption that the 
gas molecules repel each othe: according to the inverse fifth 
power of the distance. The values of these integrals, as. 
found by mechanical quadrature, are 
A, =2-6595 A, =1-3682. 
Constructing a graph of sin?@/sin*2~, I chanced to notice 
that the convexity is turned towards the axis of p, so that 
the quadrature used by Maxwell must make A, a little too 
large. With the second integral, the number of points near 
the maximum of sin?2@/sin?2@ is insufficient, so that the 
value of A, will turn out to be too small. 
Of the different methods of evaluating these two integrals, 
that of Gauss (‘‘ Methodus nova integralium valores per 
approximationem inveniendi,’? Werke iii. pp. 163-196): 
evidently leads to more accurate results than taking a 
number of equidistant points. This method of quadrature 
can be applied in two ways. The integrands sin*6/sin*29: 
and sin?2@/sin’2@ can be expanded either in power series 
i: 
of @ or of g=e "*, where K and K’ are 
complete elliptic 
integrals of the first kind. Since 
dp =2/Nq(t—4q + 6q?—8q°+13q*—124°+ « « -)dq, 
we can effect the approximate integration by finding either 
the values of or of V/q between the limits of integration, 
proportional to the roots of zonal harmonies of nth order 
P,(u), and proceeding according to the method indicated by 
Gauss. 
These tedious calculations were undertaken by Messrs- 
