418 THE GARDENER. [Sept. 



.Mr Hammond, as does also Mr Iliscocks in his first letter, together 

 with A. II., p. 269, and these results are given by apparatus in 

 actual use. In Albion's case (of which an apparatus on the same 

 principle I once had charge of, and a better working one could not 

 be), practically speaking, we have no llow-pipe beyond the expan- 

 sion box. 



At p. 375 Mr Makeczie says : "It makes no difference where the 

 highest point is," and thereby coincides with Mr Hammond. But is 

 there no waste of motive power in an apparatus fitted on a long slow 

 gradient, with a gradually decreasing temperature in the body of 

 water, and consequently an increasing density as compared with 

 one where the rise is vertical ? And is the friction in both cases the 

 same 1 ? 



At p. 374 he says : " By increasing the quantity (of piping) the 

 friction increases in greater proportion than the power ; " and at p. 

 376, " that the pressure depends on depth or height and the density 

 of the liquid, so that it makes no difference to the motive power, 

 seeing the friction in both cases must be the same." I draw attention 

 to these quotations for this reason, that we are discussing a question 

 of hot water flowing in an apparatus fitted up on a certain principle, 

 which is quite a different thing from a body of water of the same 

 temperature throughout, and being raised to a certain height by pres- 

 sure or gravitation, I shall trespass no further on your space, but 

 will be content to leave the matter to those who have better oppor- 

 tunities of carrying it to a successful issue, by proving it unnecessary 

 to have flow-pipes for hot water on a continuous ascent. 



Eobt. Stevens. 



Paston, Northumberland. 



On p. 373, owing, no doubt, to the iudistinct writing, "Torricel- 

 liana" appears for Torricelli and. On p. 375 I find that it was 

 overlooked, in copying the original MS., to alter the words " every 

 pump and chimney in the country proves," which should have been 

 " every suction-pump in the country proves." Again, on p. 377, for 

 " Deschand's Natural Philosophy," read Deschanel's Natural Philo- 

 sophy ; and for " J,, that of copper-ore, 9.44," read ^ that of copper, 

 or 9.44. 



I have no right to object to your having expunged some irrelevant 

 matter, the communication was far too long ; but at one particular 

 place this has led to an appearance of confusion, which I shall be 

 obliged by your allowing me to explain. At p. 374, after the words 



