152 
THE FLORlSr. 
Gas, as a heating agent, has frequently been tried—generally, 
however, on a small scale. But hitherto the great obstacles to its 
successful application have been the large consumption, and the 
comparatively small results obtained. Until the discovery of the 
Bunsen burner the flame produced by the ordinary jet threw out but 
little heat, and through the only partial consumption of the gas the 
bottom of the boiler to be heated became so encrusted with the soot, 
that the action of the flame, not powerful in itself, was further much 
diminished in force. The Bunsen burner appears to consume the gas 
passing through the tube completely : this is proved by the absence of 
any deposit on the bottom of the boiler. Mr. Craigie has availed 
himself of this, and not only so, but his boiler being composed of a series 
of tubes, round which the flame plays on all sides, the greatest possible 
economy of heat is arrived at, inasmuch as the greatest amount of 
surface is exposed to its action. Another difliculty was that of pre¬ 
venting the deleterious effects of the gas upon the air; this is also 
satisfactorily met. A flue ingeniously contrived passes through the 
boiler, and any injurious influence is carried away through an aperture 
in the wall. Without wood-cuts it is impossible to give a precise idea 
of the plan. Any of your readers who may desire further particulars 
will doubtless be able to obtain them through the agents for Mr. Craigie’s 
patent. I would merely add that some five or six of these apparatuses 
have been at work during the late winter and in every case satisfactorily, 
one instance being a greenhouse fifteen feet by twelve feet in which the 
glass comes down close to the ground, placed in an exposed situation. 
This was kept perfectly free from the effects of the hardest frost, with 
three burners at most to get the water up to the required temperature 
at first, and after that two burners to keep it so. 
As to the consumption of gas, the size ordinarily used is No. 2 jet; 
this consumes from two and a half to three feet of gas per hour, the 
difference in amount depending upon the higher or lower pressure of the 
gas. It will easily be calculated what the expense for twenty-four 
hours would be,—here the gas costs about six shillings per thousand 
feet. It has been stated that the expense of the apparatus would be 
about 12/.; this estimate may be correct if copper were the principal 
metal used, there seems however, to be no reason why iron should not 
do as well, in which case the cost would be diminished one half. 
The application of the gas in the way above mentioned, is not, of 
course, confined to greenhouse purposes, it is equally well suited to 
lobbies, &c. I have seen also some very neat library tables with hot 
water pipes underneath, which are calculated greatly to increase the 
temperature, and in this way are a great addition to the comfort of a 
room of that description. 
Edinburgh, * C. K. S. 
PLANTS EMPLOYED AT TBENTHAM FOR DECORATIVE 
PURPOSES. 
The following is a list of plants which are at this time useful for 
decorative purposes in these gardens. Among the flowering plants there 
