232 



THE GARDENERS' MONTHLY 



[August, 



continually increasing circle. What Mr. Siler 

 says about water for Cactuses we can confirm by 

 experience. Even pot Cactuses we plant in the 

 open ground during summer, and, whenever we 

 have very hot weather for a few successive days, 

 pour on the water, and it is wonderful how they 

 seem to enjoy it. 



In this section we find Mamillaria Xuttalliana, 

 M. vivipara, Echinocactus Simpsoni and Opuntia 

 Missouriensis entirely hardy, though singularly 

 enough it never flowers. This peculiarity follows 

 others. In Southern Utah the writer dug up 

 (with the swingle-tree of a wagon, while his wrfe 

 held the horses' heads) three large masses weighing 

 20 pounds each, of Echinocactus phoeniceus, then 

 covered with their magnificent wine-glass-shaped 

 flowers. On returning from the Pacific they were 

 found safely at home. Though they are in 

 charming health, they have not had a flower the 

 past two summers — though the dry mesa soil on 

 which they were growing, has been imitated as 

 nearly as possible. Under culture we cannot 

 always rely for success on imitating natural con- 

 ditions. We must learn from experience.- — 

 Ed. G. M.] 



THE RELATIVE COST OF STEAM AND 

 HOT WATER HEATING. 



BY W. H. PAGE. 



In your remarks at the close of an article with 

 the above heading, July number, I notice you say 

 " As a queit'ion of physics, it takes more coal to 

 heat a certain amount of water to a condition of 

 steam and keep it to a condition of steam than it 

 does to warm water." 



Now, Mr, Editor, 1 think your statement a little 

 misleading. You say, a certain amount of water. 

 Well, I will call this certain amount of water 50 

 gallons for steam and 50 for hot water. That is, 

 a certain amount for each apparatus if I have your 

 meaning of it. Now of course it will take less to 

 heat this water to the usual temperature in a 

 greenhouse circulation which will average about 

 190O than what it would to make steam. Hut. is 

 that a comparison ? I should say not. Now let 

 me put this in a light that will be more easily un- 

 derstood. In a good steam boiler I have 50 gal- 

 lons of water, sufficient to raise steam to fill the 

 whole system of circulation. In order to heat by 

 hot water all the circulation must be full and the 

 proportion for hot water would be 500 gallons. 

 Now we start a fire in the hot water boiler and let 

 it run full force, and in two hours we have the 

 water to a boiling point in the boiler and about 1 



half-way through the circulation. In the steam 

 boiler the water can be brought to a boil in twenty 

 minutes, and in ten more the whole system of 

 pipes can be brought to 212°, and at a pressure of 

 two pounds the diaft will be shut off and the fire 

 only consumed fast enough to maintain the pres- 

 sure. With the steam there is no heat for the first 

 twenty minutes, and but little from the hot water, 

 but at the end of two hours the steam boiler is 

 turning out the greatest quantity of heat and 

 working with drafts closed, while the hot water 

 boiler is burning its coal without hindrance. Th^ 

 steam boiler has been under check for one and a 

 half hours. 



My experience has been that it takes one-third 

 more coal to heat a dwelling house by hot water 

 than by steam ; and if true in this why not in 

 greenhouse heating ? With proper adjustments 

 steam is the most economical method of heating a 

 greenhouse, and can be left alone for a longer 

 time than any hot water boiler. Norwich, Conn. 



[There is not probably much difference between 

 our correspondent and us. The difference is chiefly 

 in the expression of the same idea. 



Our chief desire was to impress on the reader 

 a fact obvious enough in itself, yet apt to be for- 

 gotten in discussions, that heat can only come 

 from fuel, that the shape of boilers, or form of the 

 water (as steam or the ordinary liquid) adds noth- 

 ing to the quantity of heat in a given amount of 

 fuel. We must increase fuel to increase heat. It 

 certainly does take less coal to merely " warm " 

 50 gallons of water than to make steam of it ; and 

 yet the point made by our correspondent, that a 

 dwelling house can be heated for one-third less 

 cost by steam than by hot water, be perfectly cor- 

 rect. But this comes from the more ready distri- 

 bution of the heat, as we understand it, and not 

 from "economy in fuel," as so generally con- 

 tended for. 



Practically, as we have said, it is but the expres- 

 sion of the same idea, but we have often seen that a 

 correct statement of a principle is by far the best 

 path to the understanding of that which depends 

 on it.— Ed. G. M.] 



MANETTIA CORDIFOLIA. 

 BY CHARLES E. PARXELL. 



The cordate leaved Manettia, M. cordifolia is 

 a very beautiful, half hardy, summer flowering, 

 twining or climbing vine, belonging to the natural 

 order Cinchonaceaj. 



It is a native of Buenos Ayres, where it was dis- 



