He wrote An Astronomical Description of the late Comet (1619); Canicularia (1648); and translated Proclus' De Sphaera, and Ptolemy's De Planetarum Hypothesibus (1620).
Meanwhile the astronomical theories of development of the solar system from a gaseous condition to its present form, put forward by Kant and by Laplace, had impressed men's minds with the conception of a general movement of spontaneous progress or development in all nature.
The Mean Length Of The Year Is Therefore 3541) Days, Or 354 Days 8 Hours 48 Min., Which Divided By 12 Gives 293 G O Days, Or 29 Days 12 Hours 44 Min., As The Time Of A Mean Lunation, And This Differs From The Astronomical Mean Lunation By Only 2.8 Seconds.
Its principal, though perhaps least obvious advantage, consists in its being entirely independent of astronomical tables, or indeed of any celestial phenomena whatever; so that all chances of disagreement arising from the inevitable errors of tables, or the uncertainty of observation, are avoided, and Easter determined without the possibility of mistake.
It is interesting to note this early employment of the camera obscura in the field of astronomical research, in which its latest achievements have been of such pre-eminent value.
In the Astronomical Papers of the American Ephemeris will be found a large number of contributions from Newcomb's pen on some fundamental and most important questions of astronomy.
Die Hauptsatze der Astronomie (1836), Die Elemente der Mechanik des Himmels (1843), may be noted amongst his other purely astronomical publications.
The precision with which the path of an eclipse is laid down years in advance cannot but imbue the minds of men with a high sense of the perfection reached by astronomical theories; and the discovery, by purely mathematical processes, of the changes which the orbits and motions of the planets are to undergo through future ages is more impressive the more fully one apprehends the nature of the problem.
For thirty years he took an active part in the business of the Royal Astronomical Society, editing its publications, supplying obituary notices of members, and for eighteen years acting as one of the honorary secretaries.
The archiepiscopal palace; the lyceum, with a good library and an astronomical observatory; the seminary for Roman priests; and the town-hall are all noteworthy.