ON THE THERMOMETER 
135 
Eriocnema marmoratum, Naudin. Marbled-leaved Eriocnema {Revue Horticole , ii., 381),—Nat. Ord., 
Melastomacese § Melastomeae.—A curious dwarf herbaceous stove plant, probably perennial, remarkable for its 
chequered leaves. The stems are short, fleshy, resembling a tuber ; the leaves oblong, oval, heart-shaped at the 
base, hairy, five-ribbed, on the upper surface bright green, marked with brown stains and broken streaks of white, 
and on the under surface rich purple. The flowers are rich rose-coloured, on a short bent spike terminating a 
scape about six inches high. It requires a hot, damp, shaded atmosphere. From Brazil. Introduced in 1849. 
Flowers in summer. Messrs. Henderson, St. John’s Wood. 
Eriocnema jeneum, Naudin. Bronzed Eriocnema ( Revue Horticole , ii., 381).—Nat. Ord., Melastomacese § 
Melastomeae.—A very interesting dwarf stove herb, with ornamental foliage, and of a soft fleshy nature, resemb¬ 
ling E. marmoratum, in character. The leaves of this are dark greenish-brown or bronze colour, shining with a 
metallic lustre. The flowers are rather larger than in E. marmoratum , and grow in a scorpoid raceme. From 
Brazil. Introduced in 1849. Flowers in summer. Messrs. Henderson, St. John’s Wood. 
Nipilzea rubida, Lemaire. Bed-stalked Niphsea.—Nat. Ord., Gesneracese § Gesnereae.—A pretty dwarf 
herbaceous perennial, with a short upright stem three to six inches high, furnished with opposite ovate-oblong 
somewhat cordate leaves, bluntly dentated at the margin; the stems and leaf-stalks are red. The flowers are 
numerous—several from each axil—pure white, on peduncles three or four inches long; the corolla divided into 
roundish ovate, slightly irregular concave segments, the stamens and pistil deep yellow. Quite distinct from N. 
oblonga, and pretty when grown in a mass. From Guatemala; probably. Introduced about 1846. Flowers 
towards the end of summer and in autumn. 
Macrostigma tupistroides, Kunth. Tupistra-like Macrostigma {Ann, de Gand ., v., 183).—Nat. Ord., 
Smilacese.—A curious stemless herbaceous plant, with a soboliferous rhizome, bearing solitary lanceolate striate- 
nervose leaves, on the short suckers, along with the solitary peduncles which, in the upper part, are furnished 
with many flowers in the form of a spike ; the flowers are small, cup-shaped, flesh- coloured, having each a deep 
violet-coloured bract. From ?- Introduced to Berlin in 1847. Flowers ? 
ON THE THERMOMETER. 
By E. J. LOWE, Esq., F.B.A.S., &c. 
T HE Thermometer is an instrument which shows us the temperature of the air. From it we have 
learned that all bodies, on being heated, expand (or become increased in volume), hut each in a 
different proportion to each other; this expansion is but small in solid bodies, greater in liquids, and 
considerable in aeriform fluids. 
Temperature plays a most important part in our atmosphere, and from experiments, we are able 
to point out the laws by which it is propagated and distributed; beyond this we cannot go, for we 
know not what modifications take place in bodies whose temperature is raised or lowered, but that 
portion which we do know concerning its laws, is of the greatest moment, especially to gardeners. 
We must, therefore, content ourselves until the time shall come in which further knowledge may be 
unfolded. 
The Thermometer was invented at the beginning of the seventeenth century, by Dr. Drebbel, of 
Alkmaer, according to some, and by Professor Santonio, of Padua, according to others. The first 
thermometer consisted of a glass tube having a bulb at one extremity, the air in which, being rarified, 
the open end was plunged into a liquid; as the temperature of the tube increased or diminished, the 
an- in the bulb expanded or contracted, and the liquid in the tube rose or fell; as this instrument was 
acted upon also by atmospheric pressure, its readings were without truth. From this early period 
various experiments were from time to time tried by Boyle, Newton, Amontons, Reaumur, Michelli, 
Fahrenheit, De Lisle, DeLuc, Hook, Celsius, Sixe, Derham, Rutherford, Breguet, &c. Amontons sub¬ 
stituted spirits; Fahrenheit, mercury ; and Breguet did without either liquid or gas, his instrument 
acting by the unequal expansion of different metals. 
The construction of the thermometer in present use, is a very small tube, terminating at one 
extremity in a bulb or reservoir, which is either filled with a liquid or a gas, mostly mercury. The 
liquid must not he mixed with air, and to accomplish this, it is strongly boiled in the thermometer, 
and when the air is expelled, the tube hermetically sealed. It was necessary that two fixed points 
should be found in order that the readings of one thermometer might be compared with another, and 
fortunately, this has been very satisfactorily done; for, under the same atmospheric pressure, all 
instruments plunged in pounded ice or melting snow indicate the same point, viz., + 32° F., and all, if 
under the same pressure are exposed to the vapour of boiling water, indicate another fixed point, 
viz., + 212° F. (of course it is understood that these experiments are carried on at the level of the 
sea). These two points being found, the tube is divided into a certain number of parts, called degrees, 
