The Barr Typewriter, which appeared in several different models and versions over its relatively short production life, was very much the product of John H. Barr, a mechanical engineer and inventor who had worked for the Remington Typewriter Company until sometime around 1923.  During that time, Barr contributed patents which included that for the body of the well known Remington Portable, famous for its appearance as the first high quality four-bank portable in the early 1920's.  Barr left Remington, and went to work for the Morse Chain Company.  Morse was a manufacturer of power transmission equipment, including not only chains but reduction gears for use in ships powered by steam turbines.  It was the cooperative effort of Barr and the Morse Chain Company which led to the formation of the Barr-Morse Corporation to produce these typewriters.
The competitive environment in which the Barr appeared was one still in a state of evolution; there was yet no clear indication as to which direction the industry would proceed.  Size and price varied greatly.  The widely sold, folding and very lightweight three-bank Corona Special was still on the market (albeit enhanced with double sets of shift keys and other improvements as compared to its original form) as was a new, four bank Corona Four model.  Underwood was selling its small three-bank portable, and very shortly would market a large four bank model.  Royal was about to introduce a four bank machine as well, and Remington continued to sell its four-bank portables known for their flat profiles and geared type-bar mechanism.  What set the Barr apart from all of these machines was the fact that it employed basket shift.  Only standard typewriters had included this feature heretofore, making the Barr a pioneering effort in portables..  As far as bulk was concerned, the Barr was as large as any machine on the market or soon to be introduced.  The employment of basket shift and the size of the machine spoke well for Barr's vision.
Barr took out three patents which covered the machine.  All of these were filed in late 1925 and in 1926, leading us to believe that this is likely the earliest these machines could have been manufactured.  It should be noted that no machines appear to have employed the exact mechanism shown in the above Barr patent.  While very much of the machine matches the drawing, about half of the type-bar and key-lever mechanism does not.  The machines actually built used an even simpler "cam and slot" construction from the last bell crank member to the type bars.  Naturally, as in most patents, the applications mention possibility of variance in design while still retaining characteristics covered in the patent.  One further note of interest, mechanically, regarding these machines (aside from the very early application of basket shift) is the fact that they employed parallel key action, in which the keytops move straight down instead of in an arc.  Several years later, the new large Corona brand portables would include both of these features.  Prior to this, it had been thought that the Corona machines introduced both of these features, which is now known not to be the case.
While it is true that advertising copy for the Barr machines noted that they were generally heavier than other portables on the market, it is also true that the patents taken out by Barr stated that the machines were to be manufactured as much as possible from stamped and punched sheet metal (for body and for lever elements of the machine) and from inexpensive wire rod (for linkages.)  Thus, in building a portable at the upper end of size and weight for the day, Barr kept the actual material cost down as far as possible.  There may have been further advantages in assembly due to the simpler and lighter parts, at least theoretically again as compared to other competitive machines -- most notably that of the Remington machines, ones which were well known to Barr.  Things such as this are certainly implied in the patents.

The machines were, as noted, built by the Barr-Morse Corporation, Ithaca, New York, but in reality the production space used to make them until 1937 was actually a part of the Morse Chain Company's main plant; there was no separate typewriter plant as such.  Morse Chain's vaunted manufacturing capability was noted in ads, and it was said that since the typewriters were built there, they also enjoyed the quality and precision of manufacture accorded all of Morse's products.  There also appears to have been production in Canada, by Barr-Morse Ltd. of Montreal, beginning in 1934, of course resulting in identical machines except in decal markings.