130 REPORT — 1859. 



will carry is equal to the tons' weight of water displaced between the light 

 and load water-lines of the ship, less the weight of coals and stores required for 

 the voyage, and which for long voyages commonly amount to four times the 

 weight of cargo chargeable as freight, and it constitutes the limitation of 

 distance which the ship is able to run under steam at a given speed. This 

 inquiry is therefore essential to a due appreciation of the economic conse- 

 quences which are involved in progressive variations of steam-ship speed, 

 especially as respects the high rates of speed, which are occasionally professed, 

 but which are seldom realized, simply because there has been no recognized 

 exposition, whereby such pretensions may be judged of with reference to the 

 required consumption of fuel. In short, regarding this matter as a public 

 cause, affecting as it does the pecuniary interest of the public to the extent 

 of millions sterling per annum, my object is to promulgate, through the 

 medium of the notoriety which every inquiry obtains upon its being brought 

 before the "British Association for the Advancement of Science," a Mercan- 

 tile Steam-ship Expositor, by reference to which as a standard of comparison 

 the good or bad qualities of steam-shipping may be determined ; and this 

 surely is a public cause, for by the operation of the scrutiny which such a 

 system of comparative exposition may be expected to inaugurate and popu- 

 larize, steamers will soon become marketable, with reference, in great measure, 

 to their capabilities for economic transport service, at the speed that may be 

 required ; under the influence of this scrutiny all bad types of form and 

 vicious adaptation of mechanical system will be eradicated ; incompetency 

 in steam-ship management will become gradually eliminated, and the mer- 

 cantile transport service of the country being then performed exclusively 

 by good, well-appointed, and well-managed ships, would be performed at 

 a minimum of cost to the shipping interests, and consequently to the best 

 advantage for the interests of the public. Hitherto the dynamic charac- 

 ter of steam-ships has been a mechanical problem enveloped in undefined 

 and even delusive terms of shipping and engineering art ; consequently its 

 determination has not been based on any recognized principles of calcu- 

 lation. Hence the dynamical character of shipping has been a mystery — 

 a matter of mere assertion on the one hand, and of credulity on the other. 

 But mystery being unveiled, commercial vision will be opened, and compe- 

 tition, in shipping as in any other well-understood and open field of public 

 enterprise, will ensure the mercantile transport service of the country being 

 performed to the best advantage, and it will gradually establish and preserve 

 the just equilibrium of freight charges as between the carriers and consumers 

 of all sea-borne productions. 



Report on the present state of Celestial Photography in England. 

 By Warren de la Rue, Ph.D., F.R.S., Sec. R.A.S., fyc. 



In bringing before the Association the present Report it will be only neces- 

 sary, after referring briefly to the labours of others, to confine myself to an 

 account of my personal experience ; for, although other observers have 

 occasionally made experiments in Celestial Photography, there has not been 

 any systematic pursuit of this branch of Astronomy in England, except in 

 my Observatory, and under my immediate superintendence in the Kew 

 Observatory. 



