TUEBINE 



1041 



Tourbe in French), is a general term signifying any peat-like or earthy deposit formed 

 in swamps and afterwards dried, and is also applied to peat itself. 



TURBINE. Numberless are the varieties, both of principle and of construction, 

 to be met with in the mechanisms by which motive power may be obtained from falls 

 of water. The chief modes of action of the water are, however, reducible to three, as 

 follow : First : The water may act directly, by its weight, on a part of the mecha- 

 nism which descends while loaded with water, and ascends while free from load. The 

 most prominent example of the application of this mode is afforded by the ordinary 

 bucket water-wheel. Second : The water may act by fluid pressure, and drive before 

 in some part of the vessel, by which it is confined. This is the mode in which the 

 water acts in the water-pressure-engine, analogous to the ordinary high-pressure 

 steam-engine. Third : The water, having been brought to its place of action, subject 

 to the pressure due to the height of its fall, may be allowed to issue through small 

 orifices'with a high velocity, its inertia being one of the forces essentially involved in 

 the communication of the power to the mechanism. Throughout the general class of 

 wheels called Turbines, which is of wide extent, the water acts according to some of 

 the variations of which this third mode is susceptible. The name Turbine is derived 

 from the Latin word turbo, ' a top.' because the wheels to which it is applied almost 

 all spin round a vertical axis, and so bear some considerable resemblance to the top. 

 In our own country, and more especially on the Continent, turbines have attracted 

 much attention, and many forms of them have been made known by pxiblished de- 

 scriptions. 



Turbines for Mining Purposes. Although the horizontal water-wheel has been 

 known and employed under various forms from the highest antiquity, and has latterly 

 been improved by Foxu-neyron, Fontaine, Jouval, and others, so as to rank among the 

 most perfect of hydraulic motors, it has only recently been applied to mining uses 

 (pumping, loading, &c.), and where so employed its success can scarcely be said 

 to be yet decided. The failures may be attributed to the following causes : First : 

 The plan of causing the water to flow simultaneously through all the buckets 

 necessitates the use of wheels of small dimensions, making a very great number of re- 

 volutions per minute, and thus requiring a considerable train of intermediate gear to 

 reduce the speed to the working rate. Second : The complex nature of the ring sluices 



employed between the guide curves and the mouths of the buckets, renders them 

 uncertain in action, and from their small dimensions liable to be easily choked by any 

 VOL. HI. 3 X 



