I 
-MugMU 
ON THE BAROMETER. 
unsightly views, or shelters from cutting winds. Vacant beds in the flower garden must be frequently 
forked over, and, if they need it, may receive a dressing of leaf-mould or rotten dung. 
Should the weather prove severe, tulip beds must be protected with mats, as much against undue 
moisture as against severe cold. Auriculas and Polyanthuses must have plenty of air and a little 
water at the roots occasionally ; but keep the foliage dry, more especially the centre of the plants. 
Carnations and Picotees generally suffer more from being unduly coddled than from cold; give them 
plenty of air, but keep them rather dry both at the root and foliage. Pinks in beds must be guarded 
against snails, and after frost the soil, on a dry day, must be compressed around the roots. Should the 
weather be severe, or the winds very cutting, a few evergreen branches, stuck among the plants, and 
also in the Heartsease beds, will protect them much. 
Complete the pruning in the Fruit Garden as soon as possible, and dust the Gooseberry trees over 
with lime and soot to eradicate moss, and also to prevent the ravages of the caterpillar. This dressing 
■will also, to some extent, prevent the ravages of birds upon the buds. Finish planting fruit trees, and 
mulch those previously planted. Look over growing crops, and if the weather is favourable, run the 
hoe through the Cabbage and Spinach crops. Sow successional crops of Peas and Beans, also 
Radishes, which protect from birds and vermin. Cover Sea-Kale and Rhubarb for forcing, and attend, 
as directed last month to the hoeing and stirring of soil in favourable weather. — P. 
•:! 
9 
ON THE BAROMETER. 
ByE. J. LOWE, Esq., F.R.A.S., M.B.M.S., &c. 
THE barometer, when well understood, is a very essential instrument in the hands of the gardener 
or the agriculturist. By it we are enabled to measure the weight of the atmosphere to a great 
nicety. It is to the celebrated Italian mathematician and philosopher, Evangeliste Torrieclli, that we 
are indebted for the invention of this instrument ; this took place in the year 1643. In all probability, 
great things would have been accomplished by this eminent man had not death put an abrupt end to 
his brilliant career when in his 40th year. It was a simple experiment which showed Torricelli that 
the air possessed weight. A glass tube, which he had scaled at one end, was filled with mercury ; 
when full, ho placed his finger on the other end, whilst he inverted the tube in a dish of quicksilver ; 
on then removing the finger, he found the mercury fell to a certain height, each time the experiment 
was made ; and it at once occurred to this philosopher that the atmosphere pressed upon the quick- 
silver in the dish, and by this means forced a certain quantity into the tube, or rather, in his experi- 
ments, held a certain portion in suspension. 
We shall not linger with the description of the barometer, as the above experiment shows in so clear 
a manner its principle of action. 
In 16G4, the excellent French mathematician and philosopher, Blaize Pascal, repeated Torrieclli's 
experiment; and by using various fluids, discovered that the lighter the specific gravity of the fluid 
used, the higher was it forced into the tube. He next made two tubes exactly alike, and filled each of 
them with mercury, and placing one at the foot of a mountain, ascended with the other ; for, thought 
Pascal, the atmosphere has weight, if I ascend an elevation, and thus pass through a portion of il, 
there will not be so much pressure as in the valley; at least, so says theory ; and practice bore out 
theory, for the barometer at the base showed a pressure of 28 inches, whilst the other gradually fell as 
ho ascended, until, at the summit, it was only 24-7 inches. On descending, it again rose, and on placing 
the two side by side, they both indicated 28 inches. In 1666, the Irish philosopher. Hubert Boyle, 
found that our atmosphere was elastic, and could be compressed : and at about the same time, the 
French philosopher, Kdinc Mariottc, showed that its weight was in proportion to the pressure exerted 
upon it. The barometer has now been made to register itself in an admirable manner, by Mr Larson 
of Bath, in his " Atmospheric Recorder." 
As with every other philosophical instrument, no dependence can be placed upon the barometer, 
unless it has been found correct by comparison with a standard instrument. Ordinary barometers are 
almost always inaccurate, for various reductions and corrections are obliged to be made, and these can 
only be applied to certain instruments. Wheel barometers, and those whose mercury is confined in a 
leathern bag, must be inaccurate. S 
The following corrections ought to be attended to, in order to obtain the true reading of the DO 
<7?> ' 
