572 Application of Hot Water in Heating Hot-houses. 



But, in a pipe near the top, the head producing the velocity 

 and overcoming the friction, is the quantity the fluid rises by 

 expansion or h e ; therefore, 



A [he — =v'; whence v/^^ = *>. 

 The effect of the cohesion of the fluid does not produce a 

 sensible effect in practical cases ; but, if it had been consi- 

 dered, the result would have shown that the pipe might 

 be so small in proportion to its length as to render the velo- 

 city nothing. 



8. The coefficients to be obtained from experiment are de- 

 noted by A, e, and /. That denoted by A depends only on 

 the form of the tube or pipe at its junction to the boiler, 

 being the same for all fluids. 



For the common mode of joining (fig. 2) it is A = 42 ; but, 

 for a pipe with a conical entrance (fig. 3) it is A = 62. Now 

 the expence of the conical form renders it probable that it 

 will seldom be used; hence, 42 may be inserted in any rule 

 for general purposes. 



9. The expansion of liquids not being perfectly equable 

 by equal increments of temperature, and not the same for all 

 liquids, the easiest mode for obtaining it for any particular 

 case will be by means of a Table. 



