ACADEMY OF NATURAL SCIENCES. 11 



Mr. Harris exhibited a section of a pile, from a wharf at Rincon 

 Point, which fell a few days since, having been destroyed by the 

 boring of the Teredo, (properly a Xylotrya.') The material of the 

 pile is Oregon pine ; it had been in the water less than six years, 

 but is now completely perforated in all directions. The subject of 

 the best means of protection for piles, against attacks of the Teredo, 

 was discussed at some length by various members. 



Dr. Ayres stated that, as yet, no reliable preventive had been 

 discovered, except that of sheathing the pile with metal. Several 

 years ago the same subject came before the Academy, and Drs. 

 Ayres and Trask were appointed a Committee to investigate the 

 subject. All external applications which have been proposed fail 

 in practice, from the wearing away of the surface by the waves, 

 and they are but little better than the natural bark. It has not 

 appeared that the saving in time was equal to the expense incurred 

 by thus protecting the piles. At Boston, where there are two 

 species destructive of timber, they find no preventive, short of 

 sheathing the piles with copper. 



In the French works on this subject, it has been stated that the 

 bark affords no protection ; but, on the contrary, aids the young 

 animals in introducing themselves into the wood. This has not been 

 found to be the case in this bay, where the bark does, on the con- 

 trary, assist in preserving the timber. 



The fact was also stated, by one of the members, that the piles 

 of the wharfs in the southern part of the city suffer much from 

 attacks of the Teredo; while those of the northern portion are 

 comparatively exempt. The fact was mentioned, that piles have 

 been entirely destroyed here in six months from the time they were 

 placed in the water. 



Prof. Brewer made some remarks on the method of calculating 

 altitudes by observation with a single barometer. He gave an ac- 

 count of the methods adopted by the Geological Survey for compu- 

 tation, in cases where there was no station barometer nearer than 

 the bay, or the valley of the Sacramento. 



Dr. Trask mentioned that the weight of the Honcut meteoric 

 iron presented by him to the Academy, at the meeting of March 

 17th, 1862, was six ounces, one hundred and twenty-eight grains, 

 troy. 



