238 



Manipulations of the Dipping Compass. 



At the first square northeast of the Washington Monument^ called How* 

 ard's Woods. 6h. Sim. to Ih. 4nm. A. M. 



At the Botanical Garden of St. Mary's College, Baltimore, Ajrril 28, 

 1841. 12/i. 50m. to 1/t. 10m. P. M. 



At both localities Mr. Nicollet made observations on the same 

 day and nearly at the same hours with a similar apparatus, ma- 

 nipulating at my request in the same manner as I have jnst de- 

 scribed. The results were remarkably coincident, as have been 

 others at the same localities. 



At Howard's Woods. 



By Prof. Bache, Aug. 28, 1840, 71°34'.4 



By Prof. Locke, April 28, 1841, 71 34.3 



By Mr. Nicollet, April 28, 1841, 71 34.9 



By Maj. Graham, June 10, 1841, 71 31.9 



At St. Mary's College. 

 Prof. Bache did not observe at this locality. 

 By Prof. Locke, April 28, 1841, 71039'.2 

 By Mr. Nicollet, April 23, 1841, 71 33.6 

 By Maj. Graham, June 11, 1841, 71 33.8 



