These expeditions to California were a faint sign, perhaps, that the age of the small observatory in the U.S. was quickly passing. Lick had been the first observatory in the nation built (1888) in the mountains to obtain better "seeing" (i.e., less atmospheric disturbance). But its largest telescope was still only 36", and smaller, well-made instruments in the clear air of rural America were not yet completely outclassed. By 1917, however, with the completion of a 100" reflecting telescope at Mt. Wilson near Pasadena, it was becoming clear that the leading work in astronomy would henceforth be done with huge telescopes high atop mountains.
The Carleton astronomy program's unquestionable contributions to the growth and steady popularity of astronomy as both vocation and avocation were recognized in 1925 when the annual meeting of the American Astronomical Society was held at Goodsell. This honor can be said to have fittingly marked the beginning of the end of Goodsell Observatory's glory days.
Herbert Wilson retired in 1926, and another portent of the end of an era swiftly followed. Fath urged President Donald Cowling to discontinue the time-service that fall.
Time-signals were still being used by three major railroads, but Fath argued that the time and effort it took to send the signals were incommensurate with the now negligible publicity the service generated. In addition, it was now true that signals from the U.S. Naval Observatory were the equal or superior of the Carleton signals in accuracy - a fact which had been recognized as far back as 1914, when a receiver was mounted atop Laird Hall to receive wireless time- signal transmissions from Washington. After much discussion, the telegraphic time-signals from Goodsell were continued until December 1931, when the small company operating the wires into Northfield went out of business. What the commanding general of the U.S. Signal Corps had called, in 1881, probably the largest and best organized time-service in the U.S., succumbed to the modern age.
However, the spirit and activities of the Carleton astronomy program were far from ready for the dustbin of history. For another decade the College continued to provide time-signals to the public in Northfield, by broadcasting them over the radio. In 1926, Fath was elected to membership in the Astronomical Society of France. He was also a member of the Royal Astronomical Society, and hence the most widely honored astronomer ever to serve at Carleton. That same year he published the first edition of a book which would make both him and the College more prominent: Elements of Astronomy, which went through four editions in the next 20 years and was arguably the most popular astronomy textbook in the U.S. for the next ten years. In addition, Popular Astronomy reached a peak circulation of 1,200 (200 overseas) before the war. And a meteorological station was re-established at the College.
There was, moreover, still useful astronomical work to be done at observatories such as Goodsell. Within the next five years, Fath had the Clark telescope remounted for more effective work, and embarked on an ambitious joint program with Lick Observatory to study the relationship between the brightness and velocity of certain variable stars. In the 1930s, instructor Richard Zug, after building a double-plate camera for the Brashear refractor, would undertake some important work - in the study of galactic star clusters, the absorption of light in space, and the size of the galaxy - and receive a prestigious National Research Grant-in-Aid to develop a thermoelectric photometer, before moving on to a more advanced research facility. Zug's departure merely emphasized the inescapable fact that despite its celebrated history and continued research activity, the Carleton observatory as a place of really substantive astronomical work was not long for this world.
The vigor and buoyancy of the program in the 1930s was soon to receive an even mightier setback: World War II brought (if the pun may be excused) Carleton astronomy firmly back to earth. While Fath taught Engineering Astronomy and Meteorology to the soldiers of the Army Specialized Training Unit stationed at Carleton, there were no astronomy majors again among the civilian students until 1948. Popular Astronomy, needless to say, suffered a major disruption of its subscriptions, especially overseas. Not even the radio time-signal service survived the war.
The situation went from bad to worse. Fath retired in 1950, and the astronomy curriculum suffered a serious decline when a suitable replacement for him could not be found for four years. Gingrich, in the process of himself retiring a year later, died unexpectedly, leaving the affairs of Popular Astronomy in turmoil. The administration had no one to edit the journal, and tried unsuccessfully to negotiate a sale. At the end of 1951, the periodical ceased publication forever. It may have been just as well; some scholars have since claimed that Popular Astronomy could no longer really compete with its glossy, commercial competitors, such as Sky and Telescope (established 1941).
As, perhaps, an appropriate symbol of these setbacks, astronomy lost its independent standing as an academic department in 1950. Although a major in astronomy was still possible, for the first time since 1890 the Carleton course catalog listed only a joint department of Mathematics and Astronomy. Such a merger was an anachronism, since math was no longer the foundation of astronomy. In 1967, Astronomy was merged instead - more aptly - with the Department of Physics; it has been the Department of Physics and Astronomy from that day to this.
With the end of 70 years of publishing and the retirement of its last Who's Who astronomer - not to mention the advent of numerous gigantic optical telescopes and the blossoming of radio astronomical technology, which made the facilities at Carleton all but useless for cutting-edge research - Goodsell Observatory clearly and inevitably lost its national significance. The era when a good small observatory on the prairie could make a name for itself in astrophysics was gone. Fortunately, the College had, during those years, broadened the base of its reputation far beyond the renown of its observatory.