42 Experiments on Vegetation. 
scale than could be done individually, and with the utmost nicety 
and exactness. The whole are from Formentera to the Orkneys 
will contain nearly 22° of the earth’s meridian; and thence the 
quadrantal are of the whole meridian, extending from the equa- 
tor to the pole, being ascertained, will afford the best of all pos- 
sible standards of length and capacity, whenever it shall be de- 
termined by the legislatures of both countries to equalize their 
weights and measures by the same-common standard. ‘The 
great are deduced from these operations will be found to pass 
over a part of Spain, all France and Great Britain; Belgium has 
already followed the example of France, and has taken the stand- 
ard from the same natural source. Thus, if by this participation, 
the three nations, from their united meridian, should agree to 
take the same standard derived from it, there seems little reason 
to doubt, the rest of the world, without loss of time or difficulty, 
would follow their example. W. Munce. 
VI. Experiments on Vegetation, tending to correct some er- 
roneous Opinions entertained respecting the Effects of ihe 
tation on the Atmosphere. By Mr. J. Tarum. 
To Mr. Tilloch, 
zs 
Sir, — Paz opinion that the atmosphere is improved by vege- 
tation has been supported by so many celebrated philosophers, 
for the last forty years, that few or none doubt its correctness. 
But in spite of authority, having long observed the very great 
analogy which exists between the animal and vegetable king- 
doms in other respects, J could not but think that the anomaly 
respecting the effects supposed to be produced on the atmo- 
sphere by vegetation was incorrect ; and that a wish to discover 
in Nature a method to reconvert the carbonic acid gas, liberated 
by animals, into oxygen, had betrayed the authors of this hypo- 
thesis into an error. I shall not occupy your pages in particu- 
larizing their various experiments, which even militated against 
their own doctrine; but beg to observe, that in general they were 
not conducted in a manner so natural and correct as to warrant 
the conclusions drawn from them. To ascertain the effects of 
vegetation on the atmosphere, I contend that the vegetables sub- 
mitted to experiment ought not to be immersed in pump or car- 
bonated water, nor ina carbonated atmosphere, as that is by no 
means the natural situation of plants, or indeed of any living body. 
To expect living bodies to perform their natural functions in 
unnatural situations is an absurdity; and to avoid this, I insti- 
tvited a number of experiments which I thought more analogous 
to 
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