300 



THE GARDENERS' MONTHLY 



[October, 



every interested reader of your magazine would 

 desire. As I am about to make some changes I 

 would thankfully accept any information to gain 

 better results; I am convinced from your remarks 

 that you have this mode in practical use. Will 

 Mr. William 'Saunders and Mr. Thomas Meehan 

 please give an illustration of the operation — such 

 as the elevation of the boiler, the exact descent of 

 the pipes, etc. 



"Thanking you and your valuable contributors 

 for many useful and practical suggestions." 



[The annexed figure i is a sketch of Mr. Saunders' 

 boiler communicated to the Gardeners' Month- 

 ly for Sept., 1872. So far as we know it has always 



(Fig. 1.) 



worked very well. But we subjoin a criticism of 

 Mr. Saunders' plan as made by Dr. Fisher, of 

 Fitchburg, Mass. : 



" Looking at this matter the way I do, I was very 

 much surprised to see a sketch of an apparatus, 

 on page 263 of the September number of the 

 Monthly, given as a model, in which the descent 

 of the pipe was gradual from the commencement 

 of the flow to the end of the return. It is true 

 that in such an arrangement there would be a 

 circulation, but a little consideration will show its 

 weak point. Suppose the water, as it leaves the 

 boiler, to be at the temperature of 200O, and that 

 upon its arrival at the botton of the boiler it has 

 cooled down to 100°. The average temperature 

 of the boiler column will not be 150"', the mean 

 between the two extremes, but probably 160O or 



and as I have attempted to show in Fig. 2, the 

 basis would be a temperature of 165 for the boiler 

 column, and a temperature of 100 only for the 

 return column. This would give a more rapid 

 circulation than the other by just the difference 

 due to the specific weights of the water at those 

 different temperatures, and which could not be 



' less than one hundred per cent." 



( The criticism is of course theoretical, but is well 

 worthy of study. 



The cut Fig. 2 explains Dr. Fisher's idea. The 

 flow and return pipe being on the same level are 

 not distinguishable from each other till near the 

 boiler.— Ed. G. M.] 



Will Warm Water Run Down Hill? — 

 "G. P. C.," Taunton (we suppose Massachusetts), 

 asks for more particulars regarding Mr. Saunders' 

 method of permitting the warm water in a boiler 

 to run down hill. The answer to another corre- 

 spondent we suppose will be all he requires. 



Disease in Coleus. — " F. L. F.," Catonsville, 

 Md., writes: "I send by mail a root of Coleus 

 Verschaffeltii, and will be greatly obliged if you 

 can assign a cause for the fungus growth upon it. 

 We have had numbers of plants destroyed by this 

 disease, and desire to have if possible a preventive 

 for next year." 



[Attacked by myriads of minute insects, only 

 seen by a strong lens, the larvse penetrating the 

 tissue in every direction. Never having seen 

 Coleus in this state before, we can suggest no 

 remedy.— Ed. G. M.] 



NEW OR RARE PLANTS. 



V^ 



(Fig. 2.) 



170°, according to the arrangement of the fire. 

 The average temperature of the opposing column, 

 which includes the entire length of the pipe, will 

 not be I 50O, because the hotter end of the pipe will 

 radiate heat faster than the rest of it, and thus the 

 average will be something less than 150' , say 140O. 

 Then we have, as a basis of circulation one 

 column of water in the boiler of the temperature 

 of, say 165'J, and another one in the pipes of 140°. 

 Now if the pipes were laid level as 1 have described. 



Amasonia punicea.— In reference to this re- 

 markable new greenhouse shrub, we have the 

 following note from Messrs. Veitch : 



"This is unquestionably one of the most beau- 

 tiful flowering shrubs that has been brought un- 

 der the notice of horticulturists for many years. 

 It was introduced by us from British Guiana 

 ihrough our collector, Mr. David Burke. It is of 

 erect habit with elegant spreading foliage, the 

 leaves are of elliptic-lanceolate form, from 9 to 10 

 mches long. The inflorescence is very brilliant, 

 being particularly striking from having a series 

 of the richest vermilion-crimson Poinsettia-like 

 spreading bracts, arranged in pairs along the en- 

 tire length of the racemes which are a foot long ; 

 these bracts, the lowermost of which are 4 inches 

 long, are very persistent, remiining in perfection 

 fully two months. From the base of each bract are 

 produced pendulous tubular flowers, in twos and 

 threes, of a creamy white color, offering a strik- 



