WATKKWOKKS OF KAST LONDON 



339 



Naiic)on Bridge. 



Although the low-level bridge at the Nahoon is beino- built 

 by the Divisional L'ouneil. J think a short referenee to it may 

 be of interest. 



The totaj length of the bridge and abutments is 331 feet. 

 Ihe length of the bridge between the abutments is 261 'feet. It 

 IS constructed of 15 segmental arches. 15 feet wide at the spring- 

 ing;; the radii of the arches are 8 feet 8 inches. The width of 

 the bridge between the handrails is 20 feet. There is no para- 

 pet to the bridge, but stout wooden handrails, which, however, 

 it is expected may be carried away in the event of the bridge 

 becoming drowned. Otherwise, it is not anticipated that the 

 bridge will suffer anv damage from abnormal floods. The con- 

 crete is being reinforced with second-hand mine cable, to pre- 

 vent temperature cracks. The estimated cost of the brido-e is 



£3,000. 



Appendix. 



City Engineer's Office, 



n-i -I, , ^ East London, 



llic Mayor and Councillors, 14th August, 1918. 



East London. 

 Gentlemen, — 



We have carefully examined the tenders submitted by Messrs Blane 



Seg to'ej^rtt^follol^s:-'^"" ^"' ^^^"" '"^'^" '^"■"^'"^^ P^^"^' ^^ 

 In his report on the proposed pumping scheme, dated 21/4/17 the 

 City Engmeer sub^mtted estmiates showing the cost of pumpmg by steam 

 and electnot.v^ The estimated cost of pumping by steam fo? 330 days 

 5ifferen'/^- f^'L^i 2s. 2d., and ^y electricity, £7,622 i8s. 8d., showinTa 

 difference ot trom £400 to £500 m favour of steam. He attaches new 

 estmiates prepared m exactly the same way. showing the cost of pumping 

 by steam and electnc.ty for 240 days in the year and also for 330 days 

 These estmiates are based upon the new tenders for the pumping plants 

 and the present cost of coal and electricity. They show the ?ost of 

 pumpmg by steam for 240 days per year as being £6.320 8s. iid and bv 

 electncity. ±6,065 13s. 3d i.e., in 8s. 7d. per million for steam as 

 agamst £10 rgs. sd. for electricity. They show the cost of pumpmg' for 

 330 days m the year as bemg : for steam, £7,140 os. 6d.. and for electriciry 



efectriily:-£j\'6's.'5d. '''""' '' ''■ ^"'- ''''' "^'"'°" ^^''°"^^- ^^ 



th. ^iT^'^i ^'^"•'^ ^l^ '^°-' '" ^''^''' t^"de''' stated that they estimated 

 the cost of pimiping by steam at £6 2s. 6d. per million, and by eleZdty 

 at 6d. per B.T. unit, at £9 7s. per million gallons. Both these estima es 

 include a contingency amount, but they had made an error in he quTnt ty 

 of current needed, and they have submitted new details, which we are 

 a taching. and which show the running cost as being, under the steam 

 ZZ7y. ""YT' ^'1° ^''■.r''' ""' ^5 °^- 9id- per million gallons an^ 

 gallons ^ ^^"'''' ''^^"■'^ ^^'^91 3s. per year, or £7 15s. 2td. per million 



In the estimate prepared by the City Engineer, it has been provided 

 to pay off the whole capital cost of either plants in 25 years and the 

 mains, buildings etc. in 35 years, and to provide 2^ per cent, for depre- 

 ciation. Naturally, these percentages necessitate the provision of much 

 larger amounts ner year under the steam pumping scheme than under the 

 electrical, and this is the reason why the difference between the one and 

 the other when working for the whole year has been considerably 

 reduced. 



