54 
Report of the Judges on the 
The letter of the Board of Trade was as follows : — 
Board of Trade, Whitehall Gardens, 22nd March, 1872. 
Sir, — I am directed by the Board of Trade to enclose some copies of a 
Memorandum on " Horse-power " of steam-engines. 
Representations have been made to the Board, that the term " Nominal 
Horse-power " conveys no definite meaning. This term occurs in Section 5 of 
the ' Merchant Shipping Act, 1862,' of which a cojiy is enclosed. 
The Board of Trade will be glad to receive any observations on the subject, 
with which the Council of Naval Architects may be able to favour them. 
If some imderstanding can be come to on the point, a definition of the 
term might be agreed to, which will be accepted, not only by the mann- 
tacturers and users of engines, but by the Legislature, in the event of the 
term " Nominal Horse-power " being retained when the Statute is revised. 
I am, Sir, your obedient servant, 
(Signed) Thomas Grat. 
The Secretary, Institution of Naval Architects, Adelphi. 
The Council of the Institution appointed a Committee to con- 
sider the question, and, finally, after two months spent in fruit- 
less discussion, the Council met to consider the Report of that 
Committee. 
The result was the following letter to the Board of Trade : — 
Institution of Naval Architects, 
9, Adelphi Terrace, London, W.C, 4th June, 1872. 
Sir, — In rej^ly to your letter (M) of the 22nd March, in which you ask 
for certain advice with respect to the term Nominal Horse-power, I am directed 
to inform j'ou that the subject has been carefully considered by a Committee 
of the Council of this Institution, with the following results: — 
The Committee were unanimously of ojoinion that the term Nominal'Horse- 
power, as at present ordinarily used for commercial purposes, conveys no 
definite meaning. 
They were also unanimous in considering that the proposal contained in 
Mr. MacFarlane Gray's pamphlet could not be recommended for adoption. The 
majority of the Committee were of opinion that no formulas depending upon 
the dimensions of any parts of the engines, boilers, or furnaces could be 
relied upon as giving a satisfactory measure of the power of an engine, and 
that even if the varieties of engines and boilers now in use could be com- 
prised under one general expression for the iMwer, the progress of invention 
would soon vitiate any such expression, or formula. 
The entire abandonment of an old commercial standard, such as Nominal 
Horse-power, however inaccurate, must be a matter of considerable inconve- 
nience, and accordingly, great attention was given by the Committee to the 
question whether that standard could not be amended and retained. Among 
the many plans considered, not one received unanimous, or even general, 
approval. That which met with least objection was that the Indicated Horse- 
power, as ascertained on a trial trip, should be taken either as the Nominal 
Horse-power, or as a basis for it, being divided by a suitable divisor. 
The Committee were of opinion that, for the purposes of the Act, if any 
standard at all of horse-power is to be used with reference to the Engineers, it 
would be better to name 400 Indicated Horse-power in place of 100 Nominal 
Horse-power. 
The Committee were also of opinion that all engineers of coasting and sea- 
