as occasion demanded. In such an observatory the student would acquire every habit of nice adjustment, delicate manipulation, accurate judgment, which would be acquired in the best astronomical observatory, and the field for the mathematical discussion of his results is simply limitless.
In another aspect, too, does the foundation of such observatories hold out important promises. It must be remembered that many of our physical constants rest unfortunately upon too uncertain a basis. The velocity of electricity and the density of the earth are examples. We have to look, then, to scientific men for the establishment of these and other facts as they truly are, and besides, for the discovery of the vast number of unknown physical laws, some of which we must believe are entirely within our reach, and but waiting continued effort to declare themselves. The laws of terrestrial magnetism, the connection of the aurora borealis with other appearances, and like subjects, seem upon the point of being elucidated. It must be remembered, too, that one astronomical observatory can do the routine work for an entire country, and that, once done, it is done forever, and that any repetition of it, however useful it may be to the person making it, is yet of no original value in the world. But the vast number of unclassified facts in the domain of physics, and the almost infinite variety of its unknown laws, will supply ample work for many more physical observatories than could possibly be established. It seems decidedly to the advantage of the student and of the college that each should have the benefit of a well-appointed physical observatory, and it is certain that the class of American gentlemen who found and sustain departments of this kind in our colleges (and it is a very large class, to our honor be it said), will find, in the establishment of such an observatory as we have advocated, the pleasure which comes from effort wisely made. They will see (as they have a most undoubted right to expect to see) the immediate usefulness and benefit of their gift, and can hardly fail to have aided in the discovery of some one of the many laws of physics which lie so close to us, almost demanding discovery.
The wisest plan for the foundation of such an observatory may be found in the form of a letter in the Smithsonian Report for 1870, already referred to, and it is as an introduction to that letter that the present paper may claim to have any value.