42 



ON THE CONSTRUCTION AND USE OF 



surroundino- country on the banks of the Xortli River is occupied hy country seats, 



^ .... 



on tlic slopes and summits of ridges of low hills, and no otiensive numutaetones 



Fig. 37. 



N--i^^ 



Dr. Draper's Observatory. 



vitiate the atmosphere with smoke. Our grounds are sufficiently extensive to exclude 

 the near passages of vehicles, and to avoid tremor and other annoyances. 



An uninterrupted horizon is connuanded in every direction, except wliere trees 

 near the dwelling house cut off a few degrees toward th(> southwest. The advantages 

 of the location arc very great, and often wlun tlu' \alleys roiuid are filled with 

 foggy exhalations, there is a clear sky over tlie Observatory, the mist flowing down 

 like a great stream, and losing itself in the chasm through which the Hudson here 

 passes. 



The foundation and lower story of tlic building are excavated out of tlie solid 

 granite, which appears at the edge of tlu' liill. This arrangement was intended to 

 keep the lower story cool, and avoid, in the case of tlu' luetal retlector, sudden 

 changes of temperature. The eastern side of the lower story, howe\er, projects 

 over the brow of the hill, and is therefore freely exposed to tlu^ air. furnishing, when 

 desired, both access and thorough ventilation through the door. The second story 

 or superstructure is of wood, lined inside with lioards like the story below. They 

 serve to inclose in both cases a non-conducting sheet of air. 



The inside dimensions of both stories taken tog(>ther are IT^ feet s(piar(% and 22 

 feet high, to the apex of the dome. This space is unnecessarily large for the tele 



