349 
of the Slide of Alpnach, 
in consequence of an increase of velocity, and may be regarded 
as an experimental confirmation, on a large scale, of the inge- 
nious views of Coulomb.'” That Mr Playfair intended to avail 
himself of these hints, was quite certain, as he repeatedly de- 
clined to print the paper in the Transactions of the Royal So- 
ciety of Edinburgh, till he had matured his views on the sub- 
ject, 
M. Bossut, so early as the year 1763, had discovered that 
the friction was always a less part of the pressure in large 
masses than in small ones ; and had thus in some measure an- 
ticipated the discovery of Coulomb. Some time afterwards M. 
Lambert observed, that the resistance generated by the friction 
of the communicating parts of an undershot corn-mill, com- 
bined with that which arises from the grain between the mill- 
stones, always diminished when the velocity was increased ; and 
Mr Southern of Soho, found, by experiments on heavy machine- 
ry, that the friction never exceeded ^^^th of the pressure, which 
is even less than its average amount in the slide of Alpnach. 
We have been induced to niake these observations, in order 
to shew that the phenomena of the slide of Alpnach were in 
every respect consistent with previous theories and experiments, 
and to prevent any doubtful opinions from being propagated 
under the sanction of a distinguished name. — Ed. 
Art. XVIII.-— of Meteorological Observations made 
in North America by Dr Holyoke awe? Professor Dewey. 
The new volume of the Memoirs of the American Academy 
of Arts and Sciences, contains three series of very interesting 
thermometrical observations, of which we propose to give a brief 
abstract. 
1. Dr Holyoke'’s Observations at Salem^ during a period, of 
Thirty-three Years. 
The first series was made at Salem, in Massach assets, by Dr 
Holyoke, with Fahrenheifs thermometer, and was condnued 
without interruption for thirty-three years, from 1786 to 1818 
