OBSERVATIONS ON THE MAGNETIC DIP AND DECLINATION 373 
‘ LIL. Cambridge Observatory, Massachusetts. 
Erected in the year 1844. Latitude 42° 22’ 48.6, N.; Longitude 71° 08’ 00”, W 
The point of observation is within the small magnetic pavilion attached to this obser- 
vatory. 
The position is not the same as is reported under the No. XIX., (see page 357,) where 
observations were made of the dip by Mr. W. C. Bond and myself, with the same appa- 
ratus, on the 29th and 30th of June, 1841. The position occupied for those observations 
was the temporary observatory at Cambridge, in latitude 42° 22' 21'.3, N.; and longitude 
71° 07' 37.5, W., which was used both for astronomical and magnetic purposes, pre- 
vious to the construction of the present permanent establishment. ‘The change of 
position seems to have caused but a slight change in the dip. 
[ regretted that other duties prevented Mr. Bond from joining me in the observations, 
with this instrument, on the present occasion. I am, however, much indebted to him 
for having, very kindly, placed at my disposal all the necessary conveniences of the 
observatory. —1844, December 23d. 
NEEDLE No. I. 
Marked end. endings. Observation. ‘Temperature Dip observed. 
SS) 16 1h. 00m. P.M. 45° 74° 19'.2 
N 16 1 56 ‘ AA 74° 16’ 
Dip by thirty-two observations on needle No.1, . . . . . « 74° 17/6 
Neevue No. 2. 
S 16 3h. 20m. P. M. 43° 74° 18'.6 
N 16 4 20 . 43 74° 19’ 
Dip, by thirty-two observations on needle No.2, . . . . . . 74°18'8 
Dip, by sixty-four observations on needles Nos. l and2, .. . . . . . 74° 18'2 
Foggy, and nearly calm, during the observations on needle No. 1. 
Fog and rain, during the observations on needle No. 2. Wind from north-east. 
Barometer 28.89 inches, being very low for this locality. 
J. D. GRAHAM. 
Continuation of Major Graham’s Paper. Read April \7th, 1846 
The following table (4) exhibits the results of the observations made at Rouse’s Point, 
state of New York, on the 15th, 16th, 17th, and 18th of October, 1845, by Major Graham 
and Lieutenant Whipple, of the United States Corps of Topographical Engineers, for 
the dip of the magnetic needle, in the plane of the magnetic meridian, and in different 
azimuths. 
The instrument used was made by Gambey of Paris, and has already been described. 
