CULTURE OF THE GUAVAS. 
39 
point he appears to be in error, — an error it is true less important where steam was 
the medium of heat, and could be laid into and shut off from a portion of the pipes 
at pleasure ; but one which it is important to bear in mind in adopting- his calcu- 
lations, which were made exclusively for steam to hot-water, where such an 
arrangement is not so easily made. 
He assumes that it is necessary to have a heating power of fifty degrees above 
the outward air for hothouses, and one proportionately great for greenhouses. We 
believe it will be found that a power of 35 to 40 degrees for the former, and 20 to 
25 degrees for the latter, is abundantly sufficient. 
It is also to be recollected, that it is impossible by a circulation of hot water to 
bring the pipes to the temperature produced by steam of 2f lbs. pressure ; therefore 
an addition of at least J, perhaps 4, must be made to the quantity of pipe allowed 
in his calculations. 
It would protract this article to a length unsuited to a periodical work, were we 
to enter more fully into this part of the subject, which indeed requires more data 
and ability than we possess. 
The foregoing hints may serve to prevent any serious mistakes, in making one 
of Mr. Tredgold's formula. 
CULTURE OF THE WHITE AND RED GUAVAS. 
(PSIDIUM PYRIFERUM AND POM IFERUM). 
The White Guava (P. pyriferum) grows to a fine little shrub in the West 
Indies ; the flowers emit a very pleasant fragrance, and the fruit is a bright yellow 
on the outside, but the flesh is light red, melting, and of a pleasant taste. 
The Red Guava (P. pomiferum,) bears a fine fruit to look at, but is not equal in 
flavour to the white ; both kinds require the same treatment, part of which is 
detailed in Vol. I., page 119. 
1. Put the plants in a rich loamy soil, and let the pots be well drained with 
potsherds. 
2. During the growing season they may stand in a warm part of the greenhouse, 
give a copious supply of water and occasionally liquid manure at the roots, and 
syringe a little clear water over the tops ; but at the time of the fruit beginning to 
ripen, the supply must be lessened at the roots, and syringing wholly discontinued. 
3. Pot the plants at first in small pots, and shift them into larger as they require 
it, being careful never to allow the roots to mat ; eventually plant them in tubs or 
larger pots, where they may remain for many years without further removal. 
4. As the fruit is generally formed and ready for ripening in the autumn, it is 
best not to winter the plants until the fruit is ripened off, which is generally about 
March or April. 
