PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 743 



resembling the great phenomenon of nebula in the heavens, so 

 fast that if concentrated they would form solid spheres. The 

 glaciers, or ice streams, Avhich are accumulations of ice descend- 

 ing by gravity along valleys from high elevations, may have also 

 been active in revulsions of the earth, and upset whole countries 

 by their force, as Agassiz recently stated in his lectures on the 

 Amazon, that the flat topped hills which are found many hundred 

 miles from the sea coast, are remarka1)le for the evidences of the 

 glacial action which they display. From the gigantic terrestrial 

 or land agencies, Ave must turn to the ocean forces, the currents 

 which exercise a powerful influence in the formation and existence 

 of the globe. They are chiefly produced by winds, and extend 

 over several thousand miles in length, and nearly half as much in 

 breadth, and are of great velocity and t»f great depth. With the 

 ocean currents are also connected the tidal waves and currents, 

 the wind weaves, as also the earthquakes. The force of waves is 

 so great that on the Scotch beach a block of gneiss, weighing 

 forty-two tons, was moved five feet from its place at one time. 

 We are also at a loss to determine when the most important periods 

 or eras have taken place. If we judge from the period in 

 which the Niagara falls have receded six miles from their original 

 bed, and if we suppose that they receded at the rate of one inch 

 annually, it would have required three hundred and eighty thou- 

 sand years to perform it. 



The discussion of the selected subject was then taken up. 



Beet. Sugar. 

 The chairman said Margraflf, a Prussian chemist, first discovered, 

 in the year 1747, that the beet contained sugar. Achard, another 

 Prussian chemist, as early as 1773 made various attempts to manu- 

 facture sugar from the beet, under the patronage of Frederick the 

 Great. The death of his patron compelled him to relinquish the 

 investigation, but he resumed his experiments some years later, 

 and in 1799 presented specimens of loaf sugar from the beet to 

 the King. His report on the subject was republisshed in France 

 and attracted the attention of the Institute, but a committee from 

 this body having stated, as the results of their experiments, that 

 only one per cent of sugar could be extracted from the beet, no 

 attempt was made in France to manufacture this variety of sugar 

 mitil the time of Napoleon, who, finding the supply of sugar from 

 the cane was nearly cut ofi", ordered new experiments to be made 



