Latitude and Longitude of Yale College Observatory. 309 
dip in 1834 was at Cambridge 73° 33’, being an increase since 
1783 of 3° 52’, or about four and a half minutes per year. It 
may be considered as established, that the dip has increased in 
this country since the earliest observations, but whether it is still 
increasing at the present time seems more uncertain. ‘The ob- 
servations made at Albany and New York may excite a suspicion 
that such is not the fact. It is hoped that so important a question 
will not Jong remain doubtful. From this table of observations 
Ihave laid down the lines of equal dip for every five degrees 
upon the chart as well as I was able. These lines being deduced 
from a small number of observations, can only be considered as 
very rough approximations to the truth, and lay no claim to great 
precision. The observation at Pittsburgh seems utterly irrecon- 
cilable with the others. I can only explain the difference by 
supposing it to be a wretched observation, or else that there was 
a very remarkable local attraction, or finally, that there is some 
typographical error. If we read 73° for 78° the observation will 
agree tolerably well with the others. Few observers in the Uni- 
ted States have instruments suitable for determining the dip; yet 
it is to be hoped that such as are thus furnished will make a 
faithful use of them, so that we may soon be able to prepare a 
much more accurate magnetic chart of the United States than 
the one which is now presented to the public. 
epee 
ape . ei the Latitude and Longitude of Yale College Ob- 
; by Extras Loomis, Professor of Mathematics and 
Meee Piiiosonty 3 in Western Reserve College, Ohio. 
In the summer of 1835, being then at New Haven, I under- 
took a series of observations for determining the latitude and 
longitude of the College Observatory. The observations were 
made under many disadvantages, with instruments poorly calcu- 
lated for the purpose; yet as it is believed that the results are 
more to be relied upon than those which have hitherto been 
adopted, they are here summarily presented to the public. I know 
of no attempt worth mentioning, which had ever been made to 
determine the latitude or longitude of the College before the year 
1811. President Day, at that time made a few observations for 
