29 i ' On Met u lite Hot-houses. 
z\uTicLK v.- — On Metallic Hothouses. By Mr. Stafford, 
Gardener to Richard Arkwright, Esq., Willersloy Castle, 
neciv Cromfoid, Derbyshire. 
Gentlemen, 
I WAS very glad lo see that Mr. Mc.Murtrie took the hint you 
gave in your first number, when you "request all practical men to take 
into consideration of what materials the roofs of Hot-houses ought to 
be constructed." His observations were what I anticipated; however, 
I must beg leave to differ from him with regard to the metal roof causing 
the Pine plants to look of a yellow colour, although in the Horticul- 
tural Transactions, I observe Mr. Oldacre makes a similar remark ; and 
many persons have given me their decided opinions in favour of the same. 
My opinion is, that this badness of colour arises from a portion of the 
roots being partially decayed, for every plant I have examined has been 
i n that condition. 
This appearance always takes place in the spring, and generally be- 
fore the plant has recovered from the various checks received during the 
winter, but as the season advances, such plants always make every effort 
to regain their proper hue; and as considerable light is necessary for this 
purpose, I conceive metal roofs may answer a good end. So far I beg 
to disagree with my old friend : at the same time I well know him to be 
a man that will search out the real cause of an apparently evil efiect. All 
writers agree that plants of a sickly colour do not respire a sufficient 
portion of oxygen, and this is very evident if we observe any plant under 
the process of blanching. 
About 32 years ago, Mr. Pindar of Birmingham, (generally called the 
Patent Sash Manufacturer,) erected two vineries and a greenhouse, at 
Aston, near Der' y, for the late Joseph Walker, Esq. a man above all others 
well calculated to superintend such a work, being of the firm of Messrs. 
Walkers, Iron Founders, of Rotherham ; being situated near the spot I 
had every opportunity of observing the process, and according to the 
practice of Jordan, every part was well executed. For 16 years after- 
wards I made many observations, and can state without the fear of 
contradiction, that no houses yet erected ever produced better Grapes 
and Pines than were grown in these. The last time I saw them, how- 
ever, the roofs were in a most wretched state, I think more so than I 
ever saw any others, either before or since. The small strips of iron 
within the copper, that formed the bars, had corroded to that degree, 
that they were extended to twice their original size, and otherwise ap- 
peared going fast to decay. At the same time some wooden houses that 
had been built four times as long, had no a])pearancc of decay, although 
subjected to the same routine of crops. 
