154 
results in eighteen months of 1844 and 1845; in all twenty-one 
thousand six hundred and forty-four results.’”’ The curves obtained 
by discussing these groups ‘all agree in their distinctive character, 
and show two east and two west deflections in a lunar day, the 
maxima W. and E. occurring about the upper and lower culmina- 
tions, and the minima at the intermediate six hours. The total range 
hardly reaches 0.5’. These results agree generally with those 
obtained for Toronto and Prague. From eight thousand to ten 
thousand observations seem to be required to bring out the results 
satisfactorily, and the best results are derived from the use of both 
groups.’’* 
These discussions of the magnetic and meteorological observations 
made at the Girard College Observatory, were published zm extenso 
in the Smithsonian Contributions to Knowledge, and also in the 
Reports of the Coast Survey. Besides the three parts above men- 
tioned, nine other parts were issued, the last in 1864; all covering 
the time from 1840 to 1845, and including only the observations 
made in that single observatory. 
I have now accomplished the task which has been assigned to me 
by your Committee. I have endeavored to sketch briefly but 
clearly the progress which has been made in electrical science since 
this Society was founded, and to present the steps of this progress 
in the form of epochs, each typified by the work of one of the 
eminent men of science whose names have shed lustre upon 
the roll of its membership. The labors of these men have 
mightily contributed to advance the development of scientific 
thought throughout the world, and so to bring about that 
exceptional evolution of electrical facts and theories which is 
the distinguishing feature of the science of the nineteenth century. 
Space has not allowed me to recount all that has been done by the 
members of this Society, even in this single direction. Many 
of them are still actively pushing outward the boundaries of 
knowledge, and are laying the foundations of yet more remarkable 
achievements. The work of these men it will be the privilege 
of some future historian of the Society to chronicle. May the 
record of the contributions made by the American Philosophical 
Society to the progress of science, in the time to come, be as 
rich and as brilliant as is its record since it first came into 
existence in 1743. 
* Proc. Amer. Assoc. Adv. Science, Xiv, 83, 1860. 
