The 1.2 meter Millimeter-Wave Telescope at the Center for Astrophysics Harvard & Smithsonian and its twin instrument at CTIO in Chile have been studying the distribution and properties of molecular clouds in our galaxy and its nearest neighbours since the 1970s. The telescope is nicknamed "The Mini" because of its unusually small size. At the time it was built, it was the smallest radio telescope in the world. Together, "The Mini" and its twin in Chile have obtained what is by far the most extensive, uniform, and widely used galactic survey of interstellar carbon monoxide. "The Mini" is currently in operation from October to May each year. In the early 1970s, an astronomer at the Goddard Institute of Space Studies in New York named Patrick Thaddeus shattered centuries of precedent in the field of astronomy and bucked a trend dating all the way back to Galileo when he decided that, in order to proceed on a modest project to map the entire Milky Way, he simply did not need and in fact refused to use a larger telescope made available for his research. He wanted a small one. In an era made conspicuous by bigger, more sophisticated, and more expensive telescopes, Thaddeus insisted on a small and relatively inexpensive instrument, which he and his colleagues proceeded to build from scratch. Purpose Interstellar carbon monoxide is the best general tracer of the largely invisible molecular hydrogen that constitutes most of the mass in molecular clouds. Hydrogen is the simplest and most abundant element in the universe, and molecular hydrogen is by far the most abundant molecule. Unfortunately, under typical interstellar conditions molecular hydrogen does not emit at radio or millimeter wavelengths. Carbon monoxide, however, the second most abundant ingredient in molecular clouds, has a rich and strong millimeter-wave spectrum and it seems to maintain a fairly constant ratio with molecular hydrogen of about 1:100,000. For this reason, carbon monoxide has become the standard tracer or "stain" for the invisible molecular hydrogen which constitutes most of the molecular mass. Achievements A total of 24 PhD dissertations have so far been written based on observations or instrumental work with these telescopes. The 1.2 meter telescope has played an important or dominant role in all of the important general findings on molecular clouds (MCs) listed below. Many of these are now considered conventional wisdom but some were originally controversial (e.g., the very existence of