162 BURTON EDWARD LIVINGSTON 



terminal plate. The vertical arm is held rigidly in position by 

 means of four guy wires to the ceiling, provided with turn-buckles. 



It is unnecessary to floor over the entire surface of the 

 table, since the instruments must all travel in the same circle, 

 and the spaces between the wooden arms of the table here 

 described are closed merely at the margin, by screwing , to 

 the arms twelve properly fitted pieces of §-inch wood, 12 inches 

 wide. The margins of these are not curved. The arms project 

 a little beyond the twelve angles, and bear screw-eyes for the fas- 

 tening of the supporting guy wires. A circle is marked on the con- 

 tinuous surface thus produced, having a radius such that when 

 the bottles now in use stand against the line the centers of the 

 cups will describe a circle with a radius of 115 cm. 



In placing the instruments upon the table, it is to be remembered 

 that every cup should receive the same amount of influence due 

 to the trailing vapor blanket which emanates from the next pre- 

 ceding one. With ordinary room temperatures and the stirring 

 action of an electric fan, enough water is lost from the type of cup 

 now in use to allow of daily readings. 



