114 REPORT—1868. 
ruled in has been prepared for recording absorption-spectra. I have taken 
notes of many by this means, which is very useful. A more satisfactory 
means of measurement than Sorby’s scale appears to be required, since the 
quartz plate cannot be readily obtained of the right thickness. 
In a future Report I hope to give the results of observations which have 
now to be deferred. 
Second Report of the Committee on the Condensation and Analysis of 
Tables of Steamship Performance. 
Ar the Dundee meeting of the British Association in 1867, the Committee 
on the above-mentioned subject, consisting of John Scott Russell, Esq., F.R.S., 
William Fairbairn, Esq., LL.D., Thomas Hawksley, Esq., C.E., James R. 
Napier, Esq., F.R.S., and W. J. Macquorn Rankine, Esq., LL.D., was reap- 
pointed, for the purpose of continuing its duties as defined in the resolution 
by which it was originally appointed in 1866; and a sum of £100 was placed 
at its disposal. The Committee, as before, employed Mr. J. Quant, naval 
architect, as calculator, and have reason to be highly satisfied with the 
manner in which his duties have been performed. 
The sum of £100 has been expended. 
The contents of the Report now submitted to the Association are as 
follows :— 
List of detailed tables whose condensed results appear in the present 
Report. 
Condensed tables. 
Analyzed tables, according to the method of Mr. Scott Russell. 
Analyzed tables, according to the method of Professor Rankine, so far as 
that method is at present complete ; that is to say, taking into account eddy- 
resistance depending on friction, and wave-resistance due to shortness of 
afterbody. Just at the commencement of the Meeting to which this Report 
is presented, Professor Rankine pointed out a hitherto neglected kind of wave- 
resistance, depending on a relation between speed and depth of immersion ; 
but the data of observation necessary in order to determine its amount and 
laws have not yet been obtained. 
In explanation of the distinction between “condensed” and “ analyzed” 
tables, it has to be stated that the condensed tables contain nothing except 
quantities ascertained by measurement, observation, and experiment ; while 
the analyzed tables contain certain functions of those quantities, which 
functions are connected with theoretical views as to the probable nature and 
laws of the actions that take place between the vessel and the water. 
List of Detailed Tables whose condensed results appear in this Report. 
The detailed tables whose condensed results appear in the present Report 
consist of those which were published in the Report of the British Associa- 
tion, 1863. 
Table I—Engineer’s log of City of Dublin Steam Packet Company’s 
Steamship ‘ Munster,’ June and July, 1861. 
No information as to draught of water or displacement is given. 
CO LT 
