208 
In conclusion, the author dwelt upon the brightened moral aspect 
of the water controversy. From De Luc’s “ Idees” all trace of charge 
against the fair-dealing of Cavendish has vanished. Lavoisier is 
found making full, if somewhat tardy, amends for any wrong he did 
the English philosopher, and as De Luc and Lavoisier testify that 
Cavendish had reached his famous discovery in 1782, the most un- 
charitable must cease suspecting that he borrowed or stole it from 
Watt, who had it not to offer any one till 17 83. 
4. On the Preservation of Foot-prints on the Sea Shore. By- 
Alexander Bryson, Esq. 
The author remarked, that the impressions of the feet of birds and 
molluscs on wet sand, were liable to be effaced by the return of the 
tide ; and that their preservation was owing to dry sand blown into 
the depressions from the shore, and again covered by a layer of 
moist sand or mud by the return of the tide. In regard to tracks 
left by gasteropodous molluscs, he stated that great caution was 
necessary to distinguish them from those left by Nereids ; and in- 
stanced the case of a foot-track of a common whelk resembling the 
marks made by the Crossopodia on the Silurian slates. When the 
track of the whelk is filled up by the dry sand blown into the de- 
pression in the line of progress, no difficulty is felt in recognising it 
as the track of a gasteropod ; but should the wind blow at right 
angles to the track of the mollusc, a series of setse-like markings 
will be observed to leeward, caused by the dry sand adhering to the 
moist. In this instance, a geologist would naturally assign the 
markings to the impression of Graptolites priodon , or sagittatus ; 
and if the wind suddenly shifted to the opposite direction, another 
series of setse would be found on the other side of the mollusc’s 
track, and the observer would at once pronounce the marks due to a 
gigantic Crossopodia, or fringe-footed Annelide. 
The author also stated, that the so-called rain-marks found on 
sandstone and Silurian slates were formed by Crustacea, and 
that the cusps which geologists had supposed were the evidence of 
the force and direction of the wind during the shower, were pro- 
duced by the wind blowing dry sand from the shore, and causing a 
raised barrier to leeward of the depression, where there was more 
moisture, and consequently more adhesion of the sand. 
