A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 
“* To the solid ground 
Of Nature trusts the mind which builds for aye.” —WORDSWORTH 
THURSDAY, NOVEMBER 2, 1882 
HVDRAULIC EXPERIMENTS 
By Major Allan Cun- 
(Roorkee : Thomasen 
Roorkee Hydraulic Experiments. 
ningham, R.E. Three vols. 
College Press, 1880-81.) 
J JNDER the direction of the Indian Government there 
have been constructed a number of canals, which, 
while reaching in transverse dimensions a size not much 
inferior to the Suez or North Sea Canal, have a far greater 
length and ramify into smaller channels of enormous 
total extent. Besides these, reservoir and river works 
have been carried out of the greatest magnitude. Hence 
the Indian Government has a most direct interest in the 
‘advancement of the knowledge of hydraulics. Not only 
must hydraulic formule be used in the design of hydraulic 
works, but also in regulating the distribution of a valuable 
\commodity—irrigation water—on which large revenues 
‘depend. Yet down to a recent period the Indian Govern- 
ment has been content to avail itself of researches car- 
ried out in Europe, and chiefly in France, and has made 
no use of its splendid opportunities for scientific hydraulic 
jexperiments. When at last hydraulic experiments on a 
‘large scale were sanctioned, involving a large expenditure 
jit wasvery fortunate that the direction of them was intrusted 
to so very competent an officer as Major Cunningham. 
“Beaucoup de personnes croient que tout homme intelli- 
gent et instruit peut faire, sans grand travail de bonnes 
Jexpériences c’est une erreur qui a fait perdre beaucoup 
de temps et d’argent.’? So says M. Boileau, who is him- 
‘self one of the most careful of hydraulic experimenters. 
Major Cunningham certainly does not think lightly of his 
work. He has enormous industry ; he repeats his obser- 
‘vations again and again; he studies every detail of his 
methods; he notes the opinions of all his predecessors 
in work of a similar kind, and discusses his results with 
great lucidity. If his experiments have furnished no 
|strikingly novel laws, the fault is not his. 
! “The general result of this work may perhaps be con- 
)sidered in some ways disappointing, in that there are no 
brilliant results, no simple laws of fluid motion disco- 
i VoL. Xxvi1.—No. 679 
vered, not even a new formula for mean velocity pro- 
posed ”’ (p. 4). 
It is certainly true that when Major Cunningham passes 
from discussing the details of practical methods, where 
he is always instructive, to purely scientific questions, to 
generalising laws from the results obtained on verifying 
accepted rules, he has a rather exceptional number of 
purely negative conclusions to state. It is almost amus- 
ing to find caution carried to the extent involved in 
printing as a general result of a considerable discussion 
that the value of the coefficient in the formula for the 
discharge of a stream “depends p~rodably on the nature 
of the banks and bed, as well as on the hydraulic mean 
depth and slope.” But nevertheless we believe the prac- 
tical objects of the experiments have been obtained, and 
the outlay usefully incurred. Less of thoroughness at 
all events would have rendered the experiments useless, 
and although considering the scale of the experiments 
they seem at present rather less fruitful of definite results 
than might have been expected, yet it may be hoped that 
Major Cunningham has not made the most that can be 
made of his results. In time the new suggestion will 
come which will reduce to order the discordant observa- 
tions. In the establishment of any new general conclu- 
sions or formule in the hydraulics of streams, this store 
of data will certainly be of the greatest value. 
Of the magnitude of the work undertaken by Major 
Cunningham, it is difficult to give an adequate idea. It 
lasted over four years. The results include 565 sets of 
vertical velocity curve observations, each set including 
velocities taken three times at each foot of depth ; 545 
sets of rod float observations, each including six mea- 
surements of velocity ; 581 sets of mean velocity obser- 
vations, each including three measurements of velocity at 
ten to twenty points ; 440 measurements of surface slope; 
besides many others. In addition to all this, the tabula- 
tion and computation of the results involved enormous 
labour. The printing of the results at Roorkee, whilst it 
must have involved greater trouble and responsibility 
than similar work in this country, seems to have been 
most efficiently and accurately done. 
From the practical point of view Major Cunningham’s 
book may be regarded as an exhaustive treatise on Float 
Gauging. All the more important observations 
B 
were 
