424- Mr. G. Fairholnie on the Poioer possessed by Spiders 



very considerably to tlie South, we shall find x = 39*02522, 



y = 0-191 100, and ^ = — i— . 



Lastly, if we exclude also the Bonine islands, where it 

 appears there is a great degree of attraction, we shall have 



X = 39-023923, tj = 0-192535, and -^ = ~. And this is 



.r 269 



the result to which we have at length come, as best repre- 

 senting the whole of our experiments in the Northern hemi- 

 sphere. In this case the differences of the partial results from 

 the calculation will be as follow : viz. 



The compressions which we have deduced are almost iden- 

 tical with the mean results of the experiments made by Cap- 

 tains Freycinet and Duperrey: but they are greater than those 

 of Capt. Sabine. In order to determine whether these dis- 

 cordancies are to be attributed to local causes, to an irregu- 

 larity in the form of the spheroid, or to errors of observation, 

 it would be necessary to make other combinations by uniting 

 the experiments not only of the navigators above mentioned, 

 but also those of Captains Parry, Kotzebue and Hall: an 

 undertaking which would exceed the bounds which I have 

 jirescribed to mvself here, and which is reserved for the de- 

 tailed account of our labours. . 



LXXIIl. On the Po-doer possessed, hy Spiders to escape from 

 an isolated Situation. By George Faiuholme, Esq.* 



HAVING observed, in a late Number of the Philosophical 

 Magazine (August 1832), an article by Mr. Blackwall, 

 in which a doubt appears to be expressed of the power of 

 spiders to escape from an isolated situation by means of a 

 projected thread, I beg leave to mention a few observations 

 on that subject which were made by me some years ago, while 



* Communicated by the Autliur. 



