Continued:
By 1945 the swing had increased a little to 12.5 inches and a longer bed was listed (which, surprisingly, did not prove popular) admitting 30 inches between centres. Modifications to the screwcutting gearbox resulted in an improvement to 50 feeds (from 0.0005" to 0.016") with the threading range extended to cover 60 threads from 3 to 184 t.p.i. In 1970 further mechanical modifications were made including the fitting of a combined English/Metric screwcutting gearbox and beautifully finished dual English/metric compound-feed dials. The English/metric gearbox could generate 60 English pitches from 3 to 184 t.p.i and 50 metric from 0.25 mm to 11 mm. 
With a standard spindle run-out of less than 40 millionths, and 30 millionths being an option (denoted by a headstock badge) the  113/32" bore headstock spindle runs in super-precision angular contact ABEC5 hand-matched, 60 mm ID bearings with the front being a non-standard and very expensive type fitted with a flange. The spindle is sleeved with an adaptor bush from its standard No. 12 Jarno to a No. 2 Morse taper and carries a 3"-D-1 Camlock nose with, as one useful option, an adapter unit containing an indexing gear and graduations to assist in the cutting of 2, 3, 4, 6, and 8 multi-start threads. Fitted with a substantial mechanical lock to ease the removal of chucks the spindle is also provided with two safety devices: an electrical interlock to prevent it from running if accidentally engaged and a "Hi-lock" to prevent the engagement of backgear above 250 r.p.m. However, these features were only fitted on 'square-dial' machines, the 'round dial' having neither. Although the motor could be "plug reversed", that is, instantly changed from one direction of rotation to the other, this was also limited to no more than 250 r.p.m., a relay in the DC control box (called the anti-plug relay) pulling in and refusing reverse until the spindle stops.
Spindle-speed ranges have varied over the years with the option, on earlier lathes, of either 25 to 2000 rpm,  40 to 4000 rpm and another with a maximum speed of 3500 r.p.m. (with just the highest set available on later machines). There were no mechanical changes to the models, the only differences between them being the use of different diameter belt sheaves and recalibrated tachometers.  All versions of the lathe are fitted with the 5 : 1 reduction gearing that, on later lathes, gives 8 to 800 rpm; because the gearbox is mounted on the motor (in the cabinet base) the headstock spindle is completely isolated from whatever vibration effects the drive might create. On early lathes the headstock-mounted tachometer was mechanically driven by a gear on the spindle (the only gear in contact with it) and could read in forwards rotation only. Later models were given an improved electrical revolution counter able to read with the spindle running backwards.
As a point of interest it is not recommended to increase the top speed on 'round dial' machines. These have a headstock divided into three compartments: one each for the front and rear bearings and one for the gearbox. The bearings are lubricated by the simple expedient of letting them sit in a pool of oil - a system that is fine for slower running, but not for continuously high r.p.m.. Later revisions saw the headstock opened up into one cavity and a splash system, together with pipes, used to carry oil direct to the bearings. The leadscrew and its drive gears are used only for screwcutting - the power for sliding and surfacing feeds being fed from the headstock to the gearbox by a flat, endless belt, driven from the end of the headstock spindle and tensioned by a jockey pulley. In standard form (and bearing in mind the differences between the older and newer models) 60 English threads are available of:  3,  3.25, 3.5, 3.75, 4, 4.5, 5, 5.5, 5.75, 6, 6.5, 6.75, 7, 7.5, 8, 9, 10,11, 11.5, 12, 13, 13.5, 14, 15, 16, 18, 20, 22, 23, 24, 26, 27, 28, 30, 32, 36, 40, 44, 46, 48, 52, 54, 56, 60, 64, 72, 80, 88, 92, 96, 104, 108, 112, 120, 144, 160, 176 and 184 t.p.i. Carriage feed rates vary through fifty changes from 0.0005" to 0.016" per revolution of the headstock spindle. A combined English-metric gearbox was also built and offered as an optional extra. It is possible to cut metric threads on the ordinary lathe, but only by unbolting the cover over the automatically-lubricated gear train and substituting the appropriate translation gears.
A masterpiece of precision construction the apron is carefully laid out for ease of use - though English readers may quibble about the positioning of the carriage-traverse handwheel at the left-hand side where the operator's hand can be showered with hot chippings. Power sliding and surfacing feeds are each selected by their own instant-action lever-operated clutches, flicking a control lever up engages the feed whist a downward motion disengages it.
Of silken smoothness, the compound slide rest assembly was fitted with appropriately large and beautifully engraved dials that indicated the number of thousandths of an inch being taken off diameter - not the travel of the slide. The dials' chrome finish was softened by vapour blasting to give an anti-glare effect.
A wide range of accessories was offered and very few 10EEs came without a taper-turning attachment - the details of which varied: some having vernier scale adjusters with graduated dials - just like the English CVA lathe - others came with a "bolt-on" brass gear to turn. While a convenient and quick-to-operate  telescoping cross-feed screw was available strangely, for this class of lathe, a fixed type was also supplied that required the screw to be removed before the unit could be brought into action. In addition to the usual fixed and travelling steadies, a variety of collets and collet holders, it was, at various times possible to specify dual inch/metric feed-screw dials, a rear dovetail and tool block on the cross slide, a (very rare) multi-position cross-feed micrometer stop and the previously-mentioned dual inch/metric screwcutting gearbox. 
At times, compared with the greatly sought-after Hardinge HLV and HLV-H 12" x 20" Toolroom lathe, the Monarch equivalent, the 10" EE Precision lathe was (unaccountably) often underrated on the used market and available at a much more reasonable price. Today, with such a restricted choice of new machines,  the market for this type of lathe is very much alive with a good trade in rebuilt machines and even new ones - United Airlines, for example, taking delivery of one in August 2000. Although a very heavy machine, at around 3250 lbs, it occupies a floor area of only 29" x 60" - and hence can be easily lost within a corner of the typical American domestic garage.
Although early production figures are difficult to determine (though the factory has records of every one made) since 1955 approximately 8,000 10EEs have been manufactured. In 1946 the base price was $4,194 but by 1955 had risen, with inflation, to $7,400 and reached $9,775 by 1965. Today (2008) they retail at $79,950 - the latter figure, adjusted against the retail prices index, shows it to be not as high as might be expected ($9,775 in 1965 being equal to approximately $59,373 in 2010).
Not only the general layout but also many detail features of the Monarch 10" EE lathe were incorporated in what was, in effect, a copy, the English CVA lathe.
A very rare capstan (screw-machine) version was also built, but in what must have been very small numbers..

Complex and effective "Dial-in" screwcutting gearbox and feeds gearbox of the first version of the Monarch EE Toolroom lathe.
Although dropped after a few years' production, this arrangement continued to be used on the very similar English CVA lathe.  The threads were indicated on the top half of the Index Plate and feeds on the bottom. The gearbox was operated by the knobs 1 and 2, and the handle 3. To select feeds, the knob 2 was turned to the position marked "Feeds" and the knob 1 to any of the A, B or C "feed range" marked around its edge.  The selector handle 3 was pushed in and turned to the desired feed shown on the Index Plate and then pulled out to lock the engagement. To select threads the knob in the vicinity of 4 (not shown) was moved to select left or right-hand threads.  Knob 2 was set to the position marked "Threads" and knob 1 turned to the thread desired found within the ranges A, B or C marked on the upper half of the index plate. The selector handle 3 was pushed in and turned it until it pointed to the desired thread and then pulled out to lock it. Note the important information on the index plate concerning stud and gear positions on the gearbox drive train.

End covers removed showing the base-mounted DC motor and reduction gearbox and, at the top, the flat-belt drive system for the non-screwcutting feed to the gearbox.

A basic test for a genuine toolroom lathe is that the width of the bed should be at least equal to, or greater than, the distance from it to the centre of the spindle. In addition, the EE has saddle arms which, at 20.5", are almost half the length of the bed ways; they are aligned by four ball bearing "gibs", mounted on eccentric studs, at the end of each arm - picture below.

The micrometer dials were appropriately large and very clearly engraved with divisions that indicated the number of thousandths of an inch being taken off diameter. The dials' chrome finish was softened by vapour blasting to give an anti-glare effect.

On all but the earliest machines the drive from headstock to screwcutting gearbox was totally enclosed and automatically lubricated.  To cut metric threads the cover had to be unbolted and translation gears substituted for those already in place. An English-metric gearbox was offered as an optional extra.

The set-over tailstock had a hardened, graduated spindle of 1.75" diameter with a travel of 3.5" The handwheel was fitted with a micrometer collar.