62 J. Campbell's Astronomical Observatory. 
Art. VIIL—On a method of constructing an Observatory on a 
Dwelling-house ;* by Mr. Joun Campseu. 
Tue idea of placing a telescope sufficiently large to require a 
revolving dome upon the top of a dwelling-house is so novel, 
ner in which the thing has been accomplished, may therefore be 
acceptable to some persons, and perhaps be the means of inducing 
others imbued with a love of the sublimest of the physical sci- 
ences, to make a similar experiment. 
The house is situated in 16th Street, near the 5th Avenue. It 
is thirty feet wide, eighty feet deep, and four stories high. Like | 
most modern houses it is constructed with an under cellar, the. 
foundation walls are therefore about fifteen feet below the level 
? 
of seventy-feet from the ground. Three stout beams rest upon 
the walls across the centre of the octagon, making a base or sup 
port for the pedestal of the telescope. The floor is raised three 
feet above that of the reading-room, care being taken not to pel 
mit any thing to rest upon, or touch the three beams which 
sustain the pedestal. 
oor opens into the reading-room, and another upon a plat 
form, over the roof of the other part of the house. Opposite t 
these doors are windows for light and air. See ground plan, fig. 2 
astronomical observatory to a dwelling-house in a city, is deservin, 
amateurs in the science. The author states in a letter to the Editors, tha he wi 
an 
