12 PROCEEDINGS OF THE AMERICAN ACADEMY 



from Gambardella's portrait. He also exhibited specimens of 

 Breckenridge bituminous coal from Kentucky, from which 

 paraffine is now manufactured, specimens of which were 

 shown, together with candles made from this substance. 



Professor Horsford spoke of certain curious knolls which are 

 found in Western New York after the forests are cut down, 

 and are always indicative of the presence of gypsum. The 

 heat of the sun acting on the soil after the removal of the 

 forests, the gypsum in solution rises by capillary action to 

 sustain the evaporation, and takes on crystalline form as soon 

 as it reaches a point where the water, reduced by evaporation, 

 becomes insufficient to hold it in solution. These crystals, 

 pushing up from below, raise the ground into the form of a 

 knoll, sometimes six or eight feet in diameter, and from one 

 to two feet high. The bed of gypsum is usually found within 

 a few feet of the surface of the ground. 



Four liundred. aud forty-sixth meeting. 



January 12, 1858. — Monthly Meeting. 



The Academy met at the house of the Hon. Thomas G. 

 Gary. 



The President in the chair. 



Professor Lovering made a communication in regard to 

 the Australian instrument, called the boomerang, under the 

 following heads : — 1. Its History and Antiquity. 2. Its 

 Shape. 3. Its Use. 4. Its Mechanical Theory. 5. Its Ex- 

 perimental Illustration. He gave upon the blackboard a 

 simple mathematical analysis, to show why it deviated from 

 the vertical plane, why it retrograded, and at what angle of 

 elevation these effects were at a maximum. 



Professor W. B. Rogers made some remarks upon the 

 variations of its movements, in actual practice, from the 

 results of abstract calculation, and the cause of these vari- 

 ations. 



