33 
QO 
OBSERVATIONS ON THE MAGNETIC DIP AND DECLINATION. 
Mean of these six readings of the needle of the small theodolite, with the 
es ens ses gti ent s* fin on, - toate RO’ Bi DOos. to, DEAE GZ. 
Sixth, by the same instrument, the poles of the needle having been reversed. 
At 5h. 15m., p.m., end A. of compass box to the north,— 
peerth.oua of needic reads, . ==. . uew. «ss ss detent de) Oe Oe coat. 
OWA OU te MOCO TURE, ttt ee RE A Ag SOS 
South end of needle at 0, vernier reads, . . . 8° 34’ 
Mean of these six readings of small theodolite, with ee ae of the duedie 
rsermeu,. ss ang ee ge BO 
Mean of six readings of pen thiectlditia with idles aun, eer here ee 
Variation of theodolite needle by a mean of twelve observations upon it, . 8° 34’.7 E. 
SUMMARY. 
. Magnetic variation, by twelve observations on needle of cormpass No. 3, 
six inches long,. . . 8°41’ Hast. 
2. Magnetic variation, by twelve abiervatioris on “the needle of ecttipaii 
No. 4, five and a quarter inches long . . . 8° 45.4 
3. Magnetic variation by twelve observations on the heeille of the theodo- 
hte, Pourand e-half inches iong,:.-.-°. 065+. ret. tee Nt te OO 
Magnetic variation at Dr. Everett’s house, near the entrance of the river 
Sabine into the sea, in latitude 29° 43’ 54”, N.; longitude 93°51’ 30”, W.; 
by a mean of thirty-six observations on three needles February 29, 1840, 8° 40/.3 E. 
This day was clear, with flying clouds, and a moderate breeze from south south-east; 
the atmosphere tolerably dry. 
Remark.—It will be observed that the variation of the theodolite needle was scarcely 
affected by reversing its poles, and that the mean result obtained for the magnetic varia- 
tion by this day’s observations differs only two-tenths of a minute, or twelve seconds, 
from the mean result obtained on the 19th of February. 
V. OBSERVATIONS FOR THE DIP OF THE MAGNETIC NEEDLE. 
Date and place of observation.—1840, May 28th. At Gaines’s Ferry, (Pendleton,) on the 
west or right bank of Sabine River; Texas. Latitude 31° 28’ 15”, N.; Longitude 
93° 44’ 33”, W. 
a No. of | Polarity of| Face of Marked iMe ansolartime ‘North end of Ne jeedte|South end o of Needle “Mea ean ‘of both () nds Attached Name 
Needle, marked e nd} Instrument. side of observation | tnt | Je of Needle. Thermometer, of x | 
of needle. | of Needle. | H. M. Deg g .| Mins, §Venths, pe Of |Mins, gt enths, Dey :| Mins. &Te nths, (Fahrenheit,) Observer.) 
| | | | 
| | lA [s | 
fist off oi |x cat | E | 0.20r.0.60.08.0 (60.25.0 |60.16.5 J.D.G. 
poe | | Ww W | 1.10" Or 540.0 161 22. 0. Wet, a 0 
be foe | ow E | 141/60. 45 0 |60.23.0 |60. 84.0 | 
ans ae W | 2.13 . |61.35.0  |62.00.0 147.5 
A very light north-east wind. eae clear, and the atmosphere very dry all day. 
