On the Acceleration of the Saw, ¢c- 393 
William Maclure, Esq. President of = Society, has for- 
warded part Ist of Conybeare & Phillips’ Geology of Eng- 
Jand and Wales, the fourth number Fe Magendie’s Jour- 
nal de Physiologie experimentale et pathologique, Nos. 44 
—5—6—7—and—8, of the a. Encyclopedique, 3 Nos. 
of the Journal de Physique for January, July, and August, 
1822, and also Greenough’s magnificent Geological Map 
of Engiand, all of which have been received. 
Professor Buckland’s splendid work, the Reliquiae Dilu- 
vianae, has a o received from the author. 
~Omission.—T wo valnable boxes of specimens from the 
_ horthern tafeas: and various other parts of the United States, 
forwarded by Major Delafield to the Society in 1823, have 
not been acknowledged till now, an omission which was not 
before observed. 
2. Effect of changes of temperature on the impelling power 
of moving water. 
York (Pa.) 18th August, 1824. 
To the Editor. 
—A singular circumstance has been observed in ~~ 
de lately, which has given rise to consi derabies a 
cussion. ‘The opinions entertained respecting it by 
ea Ss 
who have turned their attention to it, are various ; nor has 
any one ee } ale to account, satisfactorily for it. This 
jded to that stock of pci which 
as been gleaning and treasuring up for the 
: serutiny of science 
au At the mouth of a creek which empties itself into the 4 
~ Susquehannah, a short distance south of the Columbia | 
bridge, there “iaids a saw-mill, which fe an Immense 
\ quantity of timber. The owners, as well as several of the 
Workmen who attend the mill, state it as a fact that at night, 
at course iven time, with the same head or quan- 
water, and without any alteration being made in 
ring, Or machinery of the mill, the saw cuts much 
more timber, than it — in the saute time in daylight : 
Vor. VIIl.—No. 50 - x 
BF 
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