626 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



That the most delicate luugs will not suffer from atmospheric 

 causes; that the healthy will feel a degree of comfort never before 

 experienced within doors; that speaking or singing becomes a 

 pleasure; that plants may be made to bloom in it as well as in 

 the conservator}'. By following the indications of this instrument, 

 at least twenty per cent, of fuel may be saved. 



Petrified Wood. 



Dr. EoAvell exhibited a very fine specimen of oak wood petrified. 

 When viewed with the microscope, it has the appearance of wood, 

 but when broken, it has the characteristics of &tone. 



Dr. Feuchtwanger said he had seen many kinds of fossil wood, 

 particularly that from Trinidad* a place well noted for many varie- 

 ties of petrified wood, but in all cases the texture of the parts 

 Vv'ould indicate the character of the tree. The greatest variety of 

 fossil wood is found in Hungary. 



Ventilator, 

 Horton's chimney top and ventilator was next exhibited. It 

 was so constructed that no current could pass through this venti- 

 lator from the outside. The wind blowing against it from any 

 point of the compass is sure to create an outward or upward draft 

 through it. 



American Institute Polytechnic Association, ? 



December 27, 1866. \ 

 Prof. S. D. Tillman in the chair ; Mr. T. D. Stetson, Secretary. 

 The chairman opened the proceedings with the following inte- 

 resting summar}' of scientific news : 



Trees of Australia. 

 There are about 120 known species of forest trees in Australia. 

 In addition to one species of Acacia, commonly known as the Black- 

 wood, the Eucalypti embrace the most important of the native 

 woods that are used for economical purposes in the blue gum, the 

 red gum, the wliitc gum, the iron bark, the box and stringy bark. 

 These are among the largest forest trees of southeastei'U Australia ; 

 and in favoraI)le situations many of them attain enormous height 

 and girth. The blue gum often reaches to nearly 300 feet, and to 

 120 feet Avithout a lateral branch. The blue gum from Tasmania 

 s extensively used in Victoria for engineering purposes, and the 

 stringy bark is chiefly employed for fencing. With the exception 

 of the red gum, these trees cannot be economically used in the 

 construction of piers and wharves, owing to the rapidity with 



