364 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Sbptkmbkr, 



therefore I liave estimated the cost of preparing plans of towns having a 

 population of 10,000, 20,000, 50,000, 100,000, 300,000. 



The levelling and marking contour altitudes in the streets embraces the 

 showing the water-shedding line, and the lines of natural drainage, as accu- 

 rately as the sinuosities of the streets will allow of their being traced, and 

 the levelling is supposed to be arranged for that particular object, as con- 

 tour lines cannot be laid out within the towns ; showing also a sufficient 

 number of contour altitudes to connect altitudes marked along the line of 

 drainage with equal altitudes marked along the water shedding lines. 



The expenses of levelling und contouring are estimated for towns situated 

 on gentle slopes. For abrupt slopes the expense of levelling will be nearly 

 one-third greater, but the contour altitudes in the streets will be at greater 

 vertical distances and fewer contour lines will be laid out. 



I have considered the towns of 10,000 and 20,000 inhabitants, to consist 

 of long brandling streets with few cross streets, and requiring less levelling 

 than towns that are compact with numerous cross streets. 



The expense of contouring or marking the contour lines outside the town 

 is calculated on the supposition that one-third of the whole area, -usually in- 

 cluded on the Ordnance plans, will admit of their being laid out, and the ex- 

 pense shown in the estimate is the average expense per acre for the whole 

 area of the plan. 



Ihe levelling performed at Windsor cost 6rf-5. per acre, including the 

 levelling for four lines of sections in addition to that which would have been 

 sufficient for sewerage and marking the contours. 



The contouring cost '2-75 per acre. 



The contours above the datum mark at the bridge are laid out at four feet 

 vertical distance from each other. 



Those below the datum point at two feet vertical distance apart. 



The expense of contouring was much increased by the necessity for laying 

 out and surveying the lines before the plan was drawn, in order to complete 

 them before Her Majesty's return to the the Castle, which caused an increase 

 of 0r/'75 to the expense. 



The cost of contouring Windsor exceeds the expense per acre, shown in 

 the estimate for towns, arising from the large extent of country in proportion 

 to the area covered by the town, the contoured area being three-fifths of the 

 area of the plan; whereas in the estimate for plans of towns the space or 

 extent of ground on which it will be possible to lay out contour lines is sup- 

 posed to be one-third only of the area of the plan. 



The cost of ascertaiuing the sewers, water-pipes, and gas-pipes of Windsor, 

 and the Castle, and putting them on the plan, amounted to \d-i per acre for 

 the space occupied by the town. 



The sewers, water-pipes, and gas-pipes of Manchester have not been ascer- 

 tained. 



The cost of obtaining them for the town of Oldham amounted to \d-\ per 

 acre. 



The sewers and water-jiipes, but not the gas-pipes, have been ascertained 

 for Bury at the expense of 0<?'28 per acre. 



The plans of Oldham and Bury are not sufficiently advanced for the inser- 

 tion of the sewers, therefore the expense of putting them on the plan is not 

 known. 



The expense of ascertaining the sewerage, water, and gas-pipes, varies ac- 

 cording to the facilities given by the local authorities in appointing persons 

 to show their position and the quantity of tlie sewerage ; some places being 

 very deficient, and few or none possess plans. 



There is not a plan of the sewers of Oldham, and only one man 80 years 

 of age, could be found who knew the situation of a principal sewer. 



I have not included contingent expenses, as office rent, conveying parties 

 or stores, as, should the Commissioners wish to undertake the surveys of 

 towns, these expenses will depend on the strength of the party or parties 

 employed, each of which, I think, should consist of 16 to 20 surveyors, to be 

 divided into two parties, when the towns nearest to each other are small, or 

 to be employed as one party if a town be large, that the survey may be 

 promptly executed. 



Estimate of the Cost per Acre of Five Feet Plans of Towns. 



METHODS OF TRACTION ON RAILWAYS. 



AlmoipheTic Pressure, Tension of a Rope, Locomotive Engines. 



There are three general methods of traction practised on railroads 

 where steyin is the motive power. 



First, by means of a rope passing over and wound up by a drum, 

 which revolves by the action of the engine. 



Secondly, by means of a tube extending the whole length of the 

 railway, and containing a solid piston, which is forced along by the air 

 being pumped out of the tube by an engine stationed atone end of it. 



Thirdly, by means of a locomotive engine which turns the wheels 

 on which it rests, and by the friction of these with the rails, carries 

 the attached train forward. 



In each of these methods of transferring the power of the engine, a 

 piirt of the power is lost in the transference. 



I. In traction by a rope some part of the power will be absorbed by the 

 friction of the rope with the road, or with the friction wheels on which 

 it is laid. Also, thi' parts of the rope between each two friction 

 wheels will hang dovvn in a curve ; force will be expended in raising 

 and straightening these segments of the rope before the train can be 

 put in rngtioDt Moregver, if the rope possess elasticity, the engine 



must first stretch the rope to a certain extent before it can act on the 

 train. It must be considered also that the engine starts not only the 

 train itself, but also with equal rapidity a heavy rope equal in length 

 to twice the distance between the two railway stations. 



These causes would operate were the trains to move on rails per- 

 fectly even, but in practice obstacles occur at the joints of the rails 

 and elsewhere which communicate shocks to the train iu motion. 

 Hence will arise another abstraction of power ; for at each shock the 

 train will be slightly retarded, and then again accelerated, and conse- 

 quently a vibrating motion will be given to the curvilinear segments 

 of rope between the friction wheels. The vibrations arising from this 

 and similar causes will be very observable in the line of rails parallel 

 to that on which the train is iu motion. The maintenance of these 

 vibrations is a fruitless expenditure of power. 



An exact illustration exists in the endless bands used for communi- 

 cating motion in steam-weaving and steam-printing, and even in com- 

 mon knife-grinders' machines -, the most casual observer must have 

 noticed the rapid vibrations of the bands in these cases. The motion 

 of the tow-ropes of river barges affords another example of these 

 vibrations. From this cause also among others, steam-tugs tow ves- 

 sels more efficiently when closely and rigidly lashed to their sides 

 than when connected by a long rope ; and a garden roller is moved 



