When one thinks of mechanical calculating machines, the Class 3 often
comes to mind. The beautiful styling, durability, and impressive sales of
this machine, manufactured between 1911-1929, are largely to thank for it's
popularity.
Many models were constructed with over 5,000 parts, with as many as 2000
moving in together at any one time. This machine was considered one
among the most technologically advanced of it's time, and commanded a
price comporable to that of a new car.
The Class 3 sports several new options such as the non-add, non-print, and individual clearing keys for each column. The moveable wide carriage also distinguishes this machine from other models.
Just by looking at the gray coloring of this machine, it's
not too difficult to date it around the WWII era. An advertisement claims
"New square keys add sureness to the touch, wings to the fingers; the
machine is pleasing in contour and color; the over-all appearance is an
invitation to get work done.
View an
advertisement for this smart new Burroughs.
The Burroughs Calculator, which so much resembled the Comptometer that
Burroughs was sued for infringement, required no more desk space than a
single sheet of paper to operate. Several keys, assuming that they
weren't in the same column, could be depressed simultaneously without
causing the tens-carry to go astray. A protection mechanism locked the
keys in a particular column if one had not yet returned. 
Though not a featherweight machine, the Portable lent itself to travel
much better than its Class 3 cousins. It's weight of about 25 pounds
must have felt exceptionally portable considering a full bodied Class 3
could easily weigh in over 50 pounds.
