NA TURE 



121 



THURSDAY, JUNE 6, 1901. 



IVA TER-PO IVER. 



An Oil/line of ilie Development and Application of the 

 Energy of Flo-wing Water. By Joseph P. Frizell. 

 Pp. vii + 563. (New York : John Wiley and Sons. 

 London : Chapman and Hall, Ltd., 1901.) 

 AXT'ATER-POWER, as developed in waterfalls, has 

 been brought prominently into notice in recent 

 years as an important source of power, owing to the facil- 

 ities afforded by electricity of transmitting it to a distance; 

 so that a small portion of the Niagara Falls and numer- 

 ous minor falls have been utilised for supplying power 

 economically for electric lighting, traction, and other 

 purposes, to places many miles distant from the falls. 

 The author, however, of this volume desires to direct 

 attention to the more widespread sources of water-power 

 contained in streams and rivers, which can be utilised 

 either by taking advantage of the natural fall by means 

 of suitable works, or by storing up the flow in flood-time 

 in reservoirs formed by constructing dams across the 

 higher parts of river valleys ; and the water thus collected 

 can be converted directly into power by using the available 

 fall below the dam, which, however, is reduced in propor- 

 tion as the water-level of the reservoir is lowered, or it 

 can be employed in supplementing the discharge of the 

 river below the dam during its low stage, so that the flow 

 when used for driving hydraulic motors may never fall 

 below a definite volume. The author points out that 

 whereas in recent times water-power has been to a great 

 extent superseded by steam-power, owing to the cheap- 

 ness of fuel and improvements in steam engines, timber 

 has already become much less plentiful in the United 

 States, and even coal will in time be exhausted ; whilst 

 the sources of water-power will always remain, and have 

 already become more available by the adoption of elec- 

 trical transmission, which in its turn has led to many 

 notable developments and improvements in the utilisation 

 of power. Undoubtedly vast sources of power produced by 

 the sun's heat are continually running to waste in rivers 

 and streams, as evidenced by the estimate quoted by the 

 author, that the power derivable from the St. Lawrence 

 and its tributaries is nearly equal to that obtainable from 

 all the coal raised yearly in the United States. The 

 difficulty consists in rendering this power economically 

 available, for a high fall and a regular flow furnish the 

 most efficient source of water-power ; whereas the fall of 

 rivers is, for the most part, moderate and spread over 

 long distances, and their flow very variable, more especi- 

 ally in the upper part of their course, where the fall is the 

 greatest. It is, therefore, quite natural that waterfalls 

 have been resorted to as a source of water-power, and for 

 transmission to a distance, especially where they occur 

 at some distance from the source of a river, and conse- 

 quently possess a more regular flow ; whereas the utilisa- 

 tion of the more ordinary flow of rivers, except for local 

 purposes, seems destined to have to wait till a consider- 

 able increase in the price of fuel and the absorption of 

 the most advantageous sources of water-power render it 

 necessary to turn to less economical supplies. Where a 

 NO. 1649, VOL. 64] 



river has a rapid fall for a considerable distance, it may 

 be quite practicable to develop largely its available 

 water-power, by regulating its flow by the construction 

 of a reservoir by means of a dam of moderate height 

 across the upper part of its valley, so as to render its 

 discharge always adequate to actuate turbines placed at 

 suitable points along its course. 



After an introductory chapter upon natural water- 

 courses, including a computation of the flo7i.'age, or rais- 

 ing of the surface and modification of the slope of a 

 stream by a dam put across it, the author treats of the 

 various forms of dams constructed across rivers and 

 streams, in ten chapters extending over 209 pages, em- 

 bracing in his descriptions fixed weirs and some forms of 

 movable weirs, as well as earthen and masonry reservoir 

 dams, with their methods of construction and some notable 

 failures. Such works, considered here as applicable to 

 the development of water-power, constitute essential con- 

 structions for the improvement of rivers for navigation, 

 and for forming storage reservoirs for the water-supply 

 of towns, which have been often described in books and 

 papers relating to these branches of hydraulic engineer- 

 ing ; and the author only enters in the latter half of his 

 book upon the consideration of hydraulic motors, and the 

 modes of transmission of the power thus obtained, which 

 more specially appertain to his subject. Three chapters 

 are devoted to the methods of conveying the water to the 

 motors, and the arrangements for the regulation of the 

 supply and the power ; whilst the various forms of water- 

 wheels and of turbines are described in two consecutive 

 chapters. .Some instances are next given of the utilisa- 

 tion of natural water-powers in the United States ; and 

 it is pointed out that the plan formerly sometimes adopted 

 of dividing a considerable fall into two or three parts, so 

 as to command a large area of ground for the mills, is an 

 expensive system in regard to the motors, and wasteful 

 of the power, and that with modern methods of distribu- 

 tion it is expedient to make use of the entire head. The 

 most important and special part of the book, however, is 

 contained in the following live chapters, in which the 

 various methods resorted to for the transmission of power 

 are considered, and some interesting examples of notable 

 power-houses are described. The forms of transmission 

 dealt with are shafting and wire ropes, hydraulic trans- 

 mission, transmission by compressed air, and electrical 

 transmission. All these methods of transmission and 

 distribution of power have their respective utility, but 

 they differ considerably in the distance to which they can 

 act with efficiency. Thus shafting is useful for trans- 

 mitting power throughout a mill or manufactory ; but 

 beyond three or four hundred feet wire ropes are more 

 economical, and can be employed with advantage up to 

 about a mile. Hydraulic transmission is valuable in 

 storing up power for intermittent working, as required at 

 docks and large canal locks ; but its efficiency for driving 

 machines at a distance of about a mile is only 50 per 

 cent. Air compressed by means of water-power has been 

 transmitted considerable distances for boring the head- 

 ings of long alpine tunnels, which it has also served to 

 ventilate ; and compressed air has been used for the 

 transmission of power in a mine in the United Stares to a- -., 

 distance of three miles ; but the changes of temperature '-'.^ 

 produced in the compression and expfinsjpnf^jof-jtti^ air> , 



