PRIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 431 



18. Ou tlie construction of catcli-water reservoirs in mountain districts, for 

 ibe supply of towns, or for manufactiu-ing purposes. 



19. Accounts of existing water-works, including the source of supply, a 

 description of the different modes of collecting and filtering, the distribution 

 throughout the streets of towns, and the general practical results. 



20. On the Lest means of improving the -water supply of the metropolis. 



21. On the structural details, and the results in use, of apparatus for the fil- 

 tration of large volumes of water. 



22. On the drainage and sewerage of large towns, exemplified hy accounts 

 of the systems at present pursued with regard to the level and position of the 

 outfall, the form, dimensions, and material of the sewers, the prevention of 

 emanations from them, the arrangements for connecting the house drains with 

 the public sewers, the best means of limiting the contamination of rivers from 

 the sewage discharged into them, and the disposal of the sewage Avhcther in a 

 liquid form, as irrigation, or in a solid form, after deodorization. 



23. On the results of the employment of steam-power on canals, and of 

 other measures for the improvement of canals as a means of conveyance for 

 heavy traffic. 



24. On iron paving, and a comparison of the results attained by it, and by 

 stone block paving, &c. 



25. A history of any fresh Avater channel, tidal river, or estuary, accompanied 

 by plans and longitudinal and cross sections, ijicludiug notices of any works 

 which may have been executed upon it, and of the effects of the works, par- 

 ticularly of the relative value of tidal and fresh water, and of the effect of en- 

 closures from the tidal area upon the general regime of sluicing wliere applied 

 to the improvement of the entrance or the removal of a bar, and of groynes, 

 or parallel training walls ; also of dredging, with a description of the machinery 

 employed, and the cost of raising and depositing the material. 



26. On the results of a series of observations, illustrative of the modifica- 

 tions which the tidal wave undergoes in its passage up and down a river, or 

 estuary. 



27. On the construction of tidal, or other dams, in a constant, or variable 

 depth of water, and on the use of wrought iron in their construction. 



28. A history of any harbor, or dock, including the reasons for selecting the 

 site, the mode of construction adopted, and the subsidiary works for the con- 

 venience of shipping, and for commercial purposes, with the cost, &c. 



29. On graving docks and mechanical arrangements having a similar object, 

 with the conditions determining their relative applicability in particular cases, 

 as dependent on the rise of tide, the depth of water, and other circumstances. 



30. Ou the arrangement and construction of floating landing-stages, for pas- 

 senger and other traffic, with existing examples. 



31. On the diff'erent systems of swing, lifting, and other opening bridges, 

 with existing examples. 



32. On the construction of light-houses, their machinery and lighting appa- 

 ratus, with notices of the methods ui use for distinguishing the different lights. 



33. Ou the measure of resistance to steam vessels at high velocities. 



34. On the results of the use of tubular boilers, and of steam at an increased 

 pressure, with or without superheating, for marine engines, noticing particularly 

 the diff"ercnce in weight and in speed, in proportion to the horse-power and tlie 

 tonnage. 



35. On the relative advantages of the principle of expansion, as applied in 

 the single long-stroke cylinder engine, in the double cylinder engine, and in the 

 three-cylinder engine, and on the adaptation of the two latter to marine pur- 

 poses. 



26. On the principles and varieties of construction of blast engines, with 

 British and foreign examples. 



