136 Remarks on Atmospheric Dust. 
one hundred years, the medium thickness of the deposit on 
- the surface of the earth in 1800 years, will not be less than 
nine feet. But Mr. R. goes farther, and supposes that in 
former times the deposit must have been much more abun- 
dant than at present. So that I apprehend we should do 
his theory ample justice, by saying that the diameter of the 
earth is now, from this single cause, twenty-seven feet sretts 
er than it was at the birth of our Saviour. But if we ex- 
amine the surface of the earth, we shall find there has ‘edad 
no such change. How happens it that rocks and stones are 
every where to be met with? — Are they made by a fortui- 
tous concurrence of atoms from aerial deposit! o the 
minerals, so various in their primitive substances, in their 
kinds and composition, which are spread all over the sur- 
face of the earth, and which are collected and form the 
cabinets of the curious, do they owe their origin to atmos- 
pheric dust? Has the iccmines the property of depos- 
iting one substance here, and another there, so as to make 
one tract of country clay, another gravel, and another rocks, 
and all lying in the same vicinity ? But without pursuing 
the subject farther, I think the ideas already suggested are 
sufficient to show that Mr. R.’s theory, instead of account- 
~ ing for any facts, is wholly irreconcileable with what we ev- 
ery where observe with respect to the operations of nature. 
UE am respectfully, your obedient servant. 
:¥oGe 
P. $.—Sir—If you think the foregoing remarks may 
ee a place in your instructive Journal, please insert 
eaten Oct. 1, 1819. 
~ Observation.—I have not the account at hand, anid only 
advert from memory to the astonishing bem of extremely 
fine, indeed impalpable dust, found not long since in the 
castle of Edinburgh, in Scotland on opening an apartment, 
and a chest containing th e Regalia of the ci-devant king- 
om. My impression ed that they had been closed ever 
since the union, viz. two centuries, and that the dust, m @ 
form light as down, was several inches thick. Whatever 
theory of atmospheric dust be adopted, this fact is very 
curious, and well worthy of being more accurately stated 
and preserved.— Editor, 
