I8h 
Proceedings of the Wei'nierian Society. 
pusilla ; Lycopodium reflexum, new to North America ; an 
Equisetum, intermediate between limosum and palustre, which 
seems to be of a new species, and which Mr Stewart proposed 
to distinguish thus : ‘‘ E. torryanum^ caulibus ramosis, ramis 
densis, hexagonis scabruisculis adpressis, spicaT terminali.” It 
differs from the two nearest species, in the sheaths, in the angles 
of the stem, in height, and in general aspect. 
At the same meeting. Professor J ameson read some observa- 
tions on Dr Bouffs comparison of the trap-rocks of Auvergne 
to those of Scotland, and showed, in particular, tliat the rocks 
of Arthur’s Seat Hill, in the neighbourhood of Edinburgh, 
must have had the same origin as those of Salisbury Crags, &c. 
March 25. — The Secretary read a communication from Mr 
Stevenson, civil engineer, relative to the state of the bottom of 
the German Ocean or North Sea, and the changes it is under- 
going ; illustrated by sections, founded on numerous soundings. 
The substance of this paper will be found in our present Num- 
ber, p. 42. At the same meeting, the Secretary communicat- 
ed the descriptions, by Mr Swainson of Liverpool, of two new 
species of Picus from the interior of Brazil. 
Art. XXXIII. Proceedings of the Cambridge PhihsopMcal 
Society. 
First Meeting., Feb. 21. 1820. — 1. Hr Thackeray pre- 
sented to the Society a curious fossil body, picked up on the 
coast of Scarborough. He afterwards read a short notice, ex- 
planatory of its locality and probable origin. 
2. The President (Professor Parish) read the first part of 
his paper on Isometrical Perspective. He first stated the diffi- 
culties he had formerly experienced in obtaining such represen- 
tations of machinery as might be sufficient to enable a common 
workman to set up the complex models used in his lectures. 
To remedy this, he adopted a perspective, in which all the 
parts of any solid are laid down on the same scale. Thus a 
cube may be represented by a hexagon, in which lines are 
drawn from the alternate angles to the centre. In this perspec- 
tive the equal lines of the solid are obviously represented by 
