364 REPORTS ON THE STATE OF SCIENCE, ETC. 
Particulars of the services in) other countries might be cited,® but the fore- 
going instances suffice to show the diversity of the systems in vogue on the 
Continent of Europe and in North America: 
9. Systems of measurement.—As described in para. 8, above, the 
authorities in other countries have adopted the direct method of measuring 
the flow itself and obtaining positive data for the study of such subjects as 
flood flows, their frequencies and magnitudes. 
In this country, however, the collection of rainfall statistics has been 
highly organised, but the direct method of measuring the flow has not been 
widely developed, with the result that the engineer who requires to know 
the yield of the rainfall, whether the quantity of water available or the 
maximum flood flow, is usually left in the position that he must make an 
approximate estimation of this by empirical formulz based upon the rainfall. 
It thus arises that, while engineers in other countries have at their command 
a store of data extending over many years for a scientific analysis of the 
subject, committees of British engineers, engaged upon the consideration of 
such important subjects as the assessment of compensation water and 
floods in relation to reservoir practice, have had to confess themselves 
hampered by an insufficiency of such data; and the engineers of catchment 
boards responsible for the control of rivers, to whom measurements of the 
river flow over a series of years are of primary importance, have, in many 
cases, to begin taking river gaugings practically de novo. 
10. Ideal to be aimed at for this country.—The organisation of a survey 
for the purpose of providing hydrometric data in connection with water 
conservancy must be considered in its broader aspects in relation to the 
general conditions and requirements of the particular country concerned. 
The various systems adopted in other countries have been referred to as 
affording some useful guidance from their example and experience rather 
than to enable a model which can be copied to be selected. ‘The conditions 
differ very materially; for instance, irrigation, which is vital in some 
countries, is of minor importance in Great Britain ; hydro-electric develop- 
ment is a necessity in many countries and is of increasing importance here ; 
floods on British rivers do not compare in magnitude with those experienced 
in some parts of America ; and in many cases there remain in those countries 
very extensive water resources as yet undeveloped. 
In Great Britain, on the other hand, the predominant interest is the ever- 
increasing need of public water supply for domestic and trade purposes, 
while, to a very large extent, the more economically available and accessible 
sources have already been appropriated and developed. Second only to 
this in importance are the problems of drainage, floods, motive power, 
navigation and fishing. 
Though the organisations of other countries, therefore, do not afford a 
model, their experience, particularly that of the United States, points to 
two important principles: (a) that the investigational activities of a survey 
should be segregated from those related to construction and administra- 
tion ; and (6) that continuous and reliable records can be collected only by 
the State; ‘those collected by other agencies, however meritorious and 
serviceable in themselves, will be liable to lack of continuity, will not be 
generally available to the public, and will be open to suspicion as to 
reliability.’ ° 
If these principles be accepted, as in the opinion of the Committee they 
should, it necessarily follows that the organisation of a water survey should 
be a national undertaking. The ideal to be aimed at for Great Britain, 
therefore, is a Government department (or section of a department) working 
® Trans. of First World Power Conference, vol. i. 10 See Memorandum B. 
