MECHANICAL AND USEFUL ARTS. 95 



cities could safely imitate, no successful method had as yet been dis- 

 covered for combining the sanitary with the economical object sought; 

 accordingly, in London, the public appeared to have acquiesced 

 in a plan which, at a vast expense, was intended to carry off the 

 filth of the city to a distance, and disregarded altogether the agri- 

 cultural value of the material itself. It was against this procedure 

 that Baron Liebig entered his protest. It might be urged by a 

 practical man, in defence of the metropolitan system, that the 

 valuable constituents of the manure were equally sacrificed under 

 the old regime as they will be when the new arrangements are 

 brought into complete operation ; that, although cesspools might 

 exist, their contents were rarely made available for the purposes of 

 agriculture, and that no more use was made of the manure, when 

 poured into the Thames in the immediate proximity to the city, 

 than will be the case now, when it is conveyed to a distance of many 

 miles. Thus, the sanitary object, at least, was provided for, whilst 

 the economical question stood upon the same footing as before. The 

 authority of chemists of great eminence might also be appealed to, 

 who reported, as the result of their investigations, that in their 

 opinion no profitable application of the sewage of London to useful 

 purposes that could be adopted on a large scale has up to the present 

 time been suggested. Those and similar reasons, however, although 

 they might serve by way of apology for embarking in the present 

 system in lieu of a better, left untouched the main argument ad- 

 vanced by Baron Liebig, and could not justify us in a blind acqui- 

 escence in the system pursued as one intrinsically good. The 

 transport of the sewage matter to a distance from the metropolis 

 had indeed become, with the present arrangements, a matter of 

 paramount necessity; but the accomplishment of that end ought by 

 do means to stifle the inquiry as to w T hether some means ought not 

 to be devised for rendering the same material available for useful 

 purposes. If the citizens of London were as fully impressed as they 

 ought to be with the importance of the subject, if they could realize 

 the enormous pecuniary loss they are at present sustaining by the 

 system pursued, they would not quietly acquiesce in the report of 

 those chemists who have expressed doubts as to the practicability of 

 employing their sewage for agricultural purposes, but would persevere 

 in putting both science and capital into requisition until the difficul- 

 ties had been surmounted. 



W find in the Scientific American, a suggestion from a Corre- 

 spondent in Buffalo, who proposes to drain cities by sinking vaults in 

 the bottoms of sewers for the reception of solid matters, which are 

 to be removed from the vaults periodically. This plan was patented 

 and brought to the notice of the London Metropolitan Board of 

 Works a year or two since by His Honour Commissioner Fane, of 

 the Bankruptcy Court. 



INDURATION OF THE STONEWORK OF THE HOUSES OF PARLIAMENT. 



During the past year, the full extent of the certainty of the decay 



