TRANSACTIONS OF SECTION G. 749 



If the feet on the gauges were painted with the actual height above the Ordnance 

 datum, it would facilitate comparison. 



At important points on large streams automatic recording appliances might be 

 placed under the direct charge of the county surveyor, who at such points might 

 daily ascertain the number of cubic feet of water carried down. Where a river 

 basin extends through two or more counties, the provision for joint action of a 

 ' Watershed Board ' seems to be already provided for, or suggested, by the Local 

 Government Act of last year. 



The author hoped the Committee of the Section would think the matter of 

 sufficient importance to bring it before the Council, and that they would be in- 

 clined to concert such measures as would bring his suggestions, or a modification 

 of them, before the Local Government Board, with the view of their giving the 

 necessary sanction for such observations being carried out by the county officials. 



5. Central Station Heating and Power Supply. Boston, U.S. (PralVs 

 System). By Wilson W. Phipson, M.Inst.C.E. 



The author commences his paper by commenting upon the growing necessity of 

 a central heating and power supply for cities and large towns, and of the dangers 

 and inconveniences of the present system. He takes for his model the scheme 

 in successful operation since 1887 in Boston, U.S., which is known as the Prall 

 System, and exemplified by the Boston Heating Company. 



This svstem consists in the constant circulation of water at a high temperature 

 and pressure (viz., at 400° Fahr., and 250 lbs. on the square inch) from the 

 batteries of boilers at the central station through the supply mains, and back to 

 the boilers by means of the return mains, the circulation being maintained by 

 means of pumps. 



The ample scope of the system is next entered upon, showing that it is quite 

 adequate to meet all requirements as regards both heat and power. 



The method of determining the amount of heat or power supplied to the con- 

 sumer is described. 



With regard to the loss of heat by radiation, it has been reduced to a minimum 

 by covering the mains with a non-conducting material, reducing the internal tem- 

 perature of 400° of the pipe to 110° on the outside of the covering. 



The area of the plant of the Boston Heating Company is shown by an accom- 

 panying map. 



The construction of the pipe trenches, or conduits, is described, together with 

 the sizes of mains, &c. 



The details of the construction of the mains are fully given, showing that 

 expansion-joints are used, which are fixed at every 100 feet to 150 feet, as well as 

 one where the main changes direction, and of the special connection used in 

 coupling the pipes together. Service-boxes to supply three houses are fixed imder 

 the footpaths, which are connected to the mains by a pipe 1" in diameter. From 

 these boxes the house supply is taken by means of copper pipes \" to 1'' in dia- 

 meter. At the end of the copper pipe, and inside the house, is fixed a vessel called 

 a ' converter,' whose use is to permit the water to resolve itself into steam, the 

 pressure of which is controlled by means of a reducing valve fixed on the copper 

 pipe before it enters the converter. From this converter the house services are 

 taken. If a supply of both heat and power is required, double or compound con- 

 verters are used with two reducing valves, the power being taken from one and 

 the heat from the other. 



The pumping and boiler capacity of the central station are given, together with 

 the latest additions to ensure economy of labour. 



The paper concludes with the hope expressed by the author to see a successful 

 central supply of heat and power syi^tem adopted in this country, and his thanks to 

 Mr. A. V. Abbot, chief engineer to the Boston Heating Company, for his kind 

 assistance in giving all possible data on the subject. 



