180 PROCEEDINGS OF THE AMERICAN ACADEMY 



Professor Agassiz gave additional facts respecting the circu- 

 lation of insects, and showed in the larva of the mosquito 

 how true vessels, destined for the caudal bronchiae, arise as 

 branches from the main tracheal tubes. 



Three hundred and twenty-third meeting. 



November 6, 1849. — Monthly Meeting. 



The President in the chair. 



The President exhibited a model of the great wooden dam 

 recently erected across the Connecticut River, at Hadley, 

 and explained the means by which it was kept from floating, 

 or from being carried down the stream. 



Professor Horsford made a further communication upon the 

 spheroidal state of water. He illustrated, by experiment, a 

 phenomenon occurring when water is carefully dropped into 

 a hemispherical capsule of polished platinum. The mass 

 having been made to rotate by directing the drops of water 

 obliquely upon the side of the capsule, at a certain stage the 

 irregular motions and shape were resolved into a series of 

 vanishing and reappearing indentations in the margin of the 

 spheroid, of wonderful regularity and beauty. This scolloped 

 edge was occasionally replaced with a series of wave inter- 

 sections, exhibiting at the surface of the water systems of 

 lozenges flitting from the circumference to the centre, dimin- 

 ishing till they vanished. 



Professor Horsford suggested that the phenomenon might 

 be due to the rotation of the mass, and its motion across the 

 bottom of the capsule from one side to the other, tending, as 

 the mass moved outward, to its elongation, and to contraction 



The probable explanation is this. After firing the wood and shutting off the 

 draft, destructive distillation commences. Inflammable gases issue ft-om the 

 wood, which, mingling with air derived from the pipe or remaining still uncon- 

 Bumed, furnish an explosive mixture, which the first jet of flame, or perhaps tlie 

 incandescent coal, causes to explode. 



" As these accidents are not of frequent occurrence, it may be found that the 

 probability of producing inflammable gases in the required quantity is less with 

 some varieties of wood than with others." 



