Impressions of Rain-drops in Strata. Tl 



ville, some of which are marked by the drops of a heavy but 

 transient shower which fell on the 21st of July 1849. The 

 average size of the hemispherical cavities is small, but some 

 of them are no less than half an inch in diameter. Many of 

 them are circular, but in some the longest diameter exceeds 

 the shortest by ^th, or even ^d. They are surrounded by a 

 small rim of mud, consisting of the matter which has been 

 forcibly expelled from the pit by the falling drop ; and this 

 marginal rim sometimes projects as much above the plane of 

 the stratum, as the bottom of the pit extends below it. In 

 those impressions which have been made when the wind was 

 blowing, and when the rain fell obliquely, the cavities are 

 not only of an oval shape, but all deeper at one end than at 

 the other. Footprints of birds, and the winding tubular 

 tracks of annelids are seen on the same surface with the 

 rain-prints. On splitting open slabs formed by numerous 

 thin layers deposited by successive tides, impressions of pre- 

 vious showers are seen, and casts of the same, standing out 

 in relief on the under surface of incumbent layers. 



The Lecturer next considered the nature of certain small 

 protuberances, which might, on a cursory view, be mistaken 

 for casts, which project from the upper surface of certain 

 layers of mud, and are caused, some of them by dried bubbles 

 of mud, and others by small particles of solid matter, covered 

 with a film of mud. He also distinguished between the cavi- 

 ties produced by air-bubbles rising up through the mud, 

 which give rise to cavities differing in shape from those 

 formed by rain, as he has proved by several experiments. 



In illustration of the foot-tracks of quadrupeds, such as the 

 musk-rat, the mine, the dog, and others, so common on the 

 recent red sand of Kentville, on the borders of the Bay of 

 Fundy in Nova Scotia, Sir C. Lyell exhibited a copy of a brick 

 one foot square from Babylon, now in the British Museum, 

 on which the track of a small animal of the Ichneumon tribe, 

 apparently the Asiatic Mongoose, is distinctly seen. This 

 brick has been sun-dried (not baked in a kiln), and must have 

 been traversed by the creature, when the clay mixed with 

 straw was still very soft. In the middle of the brick is an 

 inscription in the Babylonian cuneiform character, which 



