464 Extracts from the Proceedings of the British 



destroys the hoards of meat and fish laid up by the natives, when 

 they have accidentally left a crevice by which it can enter. 

 When its retreat is cut off it shews its teeth, sets up its hair, 

 arches its back, and hisses like a cat. It will seize a dog by the 

 nose and bites so hard, that unless the latter is well used to the 

 combat it escapes. Easily tamed it soon beeomes attached to 

 its master, but is not docile. The flesh is occasionally ^aten, 

 but not prized by the Indians. The females are smaller than the 

 males, go with young about six weeks, and produce from four to 

 seven at a time, about the end of April. When caught in traps 

 this species is often devoured by its n6ar relation the Fisher. Pen- 

 nants marten (Mustela Canadensis.) 



As an article of commerce and of luxurious and ornamental 

 dress, the fur of this animal is well known. It is said that 100,000 

 skins are annually taken to Britain. Yet as the species is very 

 prolific, it is still a common animal in the large forests. In the 

 settlements, however, it soon becomes exterminated. The fox lin- 

 gers around among the agriculturists, and pays his attentions to- 

 the farm-yard long after the marten has left the' scene of advancing 

 civilization. 



ARTICLE XLII. — Extracts from the Proceedings of the British 

 Association for the Advancement of Science. Dublin,. 

 August 26, — September 2, 1857. 



Section A. — Mathematical and Physical Science. 



Professor ITennessy read a paper on the Direction of Gravity 

 at the EartKs Surface. For all practical purposes, he said, the 

 direction of gravity was consideied perpendicular to the earth's 

 surface ; and a similar assumption was often made in writings 

 claiming a high degree of scientific accuracy. This arose from 

 defining the earth's surface as the surface of equilibrium of the 

 waters. If the earth were stripped of its fluid covering, the irre- 

 gular surface so laid bare might be intersected by a surface so 

 placed that the volume of all the eminences rising above it would 

 be equal to the volume of all the depressions. With the data at 

 present possessed it would be nearly possible to have the mean 

 surface. They were not in a position to say how far it approached 

 or diff'ered from a surface of equihbrium, or in other words, they 

 could not assume that gravity was rigorously perpendicular to such 



