In a Nutshell
103 years old and looks gorgeous - and still works for you as business and entertainment centerpiece

Introduction:
There is still no better introduction into a business phonograph than the 1910 movie "The Stenographer's Friend; Or, What Was Accomplished by an Edison Business Phonograph", starring Marc McDermott as office manager and John R. Cumpson as assistant. The phonograph I am going to present is almost identical to the one advertized in this original Edison commercial.

After having sold a Business Phonograph Model C in 2009 (ref.1) I here present the extremely rare 1912 Model D in metal cabinet with Japanned enamel finish. The phonograph invented by Thomas Alva Edison [1847-1931] in 1877, in the beginning was used as a business dictation device and was rented for amusement in "phonograph parlors". In 1878 Edison made a list for the uses of his phonograph. Number 1 of 10 points: "1. Letter writing and all kinds of dictation without the aid of a stenographer". After inventing it, Edison lost interest and worked for his incandescent light bulb. In 1880 he started again by developing the Perfected Phonograph, already featuring the "spectacle" shaped double head for recording and play-back, as found in my machine. These early phonographs were all electrically powered, even the 1894 Class M (battery) and Class E (110V DC), relatives of the Perfected. Edison rented them out for $40/year again mainly to businesses and tried to sell them as dictation machines, but later converted them for use in phonograph parlors. In 1890 he had bought his company back from ill Jesse H. Lippincott [1842-1894], and after declaring bankruptcy in 1894, and thereby also getting back his rights on the phonograph, he started to build first machines for the home entertainment market, the "Class M Home" (1893), the "Amet Motor" (1895), the "Spring Motor" (1896), the "Home" (1897), the "Standard" (1898) and the "GEM" (1899) phonographs, the technically limited GEM selling for $7.50 only.
Originally neither Columbia's Graphophones nor Edison Phonographs did well for office use: too short recording time, expensive machines ($225 for a Class M), messy batteries, mechanical problems. Edison introduced a new "Business Phonograph Model C" in 1905, Columbia named their new machines "Dictaphones", and by 1908 (the year when the Edison Business Phonograph Company was incorporated), not least with the help of government agencies and big companies like Sears Roebuck, sales started to go up. Model C was updated in March 1907 to Model D, with details of the spectacle frame carrier arm changed, a recording horn held by a short crane on front of case added, and coming on a 4-post steel knock-down pedestal with casters and a single shelf. With the introduction in 1912 of the School Phonograph (a late version of the Opera, but don't confuse it with Victor's Schoolhouse Phonograph) also the D got a new metal cabinet with black enameled ("Japanned") finish, that however stayed moulded and shaped like the previous oak cabinets. A large gilt decal "Edison" in signature style decorated the front of both new phonographs, which incidentally both are extremely rare. Note that not before 1918 Edison called his dictation machines "Ediphones". There is evidence for a last Business Phonograph Model E (looking already like an Ediphone), but I don't know production numbers. Mainly 3 motor choices were offered: Universal AC, DC, and spring motors, the electric motors outnumbering the spring motor version 25:1. This is the second reason my double spring phonograph is so rare. The third reason is its completeness and condition (see below).

Additional information:
ref.1: http://www.greenhillsgf.com/Project_Edison_Business-C.htm
ref.2: http://www.officemuseum.com/dictating_machines.htm

About my Business Phonograph:
The phonograph offered in Edison's 1910 movie above is an electrical motor model D from 1907. Already equipped with the new dictating horn and crane it still has the traditional oak cabinet. The model D offered here is a very rare version from 1912, offered when Edison introduced his "School Phonograph", a late version of the "Opera" and the last outside horn phonograph. My D is exceptionally complete with original knock-down pedestal, stamped dictation horn with Kreiling TIZ=IT connector and crane, rubber dust cover with faded Edison signature, and both business reproducer and -recorder. The machine even has its original (repainted) shavings tray, memorandum sheet (Auto Dictation Index) with pencil holder (and possibly original pencil). The phonograph has not only the obligatory end-of-cylinder bell but also the double spring motor has a bell alarming when the motor needs rewinding (motor wound-down bell, see below). Please e-mail me (Kris) for any questions, ich spreche Deutsch, je parle Français.

Myths and Facts:

"A business phonograph cannot play music"
Wrong: A business phonograph reads and writes cylinders with 150 tpi (tracks per inch), whereas a 2-minute machine reads and writes 100 tpi and a 4-minute machine reads 200 tpi cylinders. Cylinders thus have to be played on the proper machine type. Recording speeds in the beginning were at about 90 rpm (revolutions per minute) and later standardized at 120 rpm, independent of the record type. This is why every phonograph has a speed control regulated by a governor. A Blue Amberol cylinder (200 tpi) of 4" length, with a fill factor of 60%, played at 120 rpm, therefore takes 4(")x 0.6 x 200(tpi)/120(rpm)=4 minutes.
The above discussion does not conclude that no music can come from a business phonograph. Since the speed is about the same, the quality of music is in fact the same for all machine types. The difference comes when the total capacity is considered. Since Ediphone cylinders, used on business machines are 50% longer in size than normal (6"), and track density is 50% higher than on 2-minute machines, the total time is 4½ minutes compared to 2 minutes, even exceeding the one of 4-minute machines. Of course in practice recording speed was reduced when dictating, so allowing dictations to extend way beyond 4½ minutes. Each machine can play back whatever it recorded before, be it Wagner's Valkyrie or Grand-mothers spoken last will.
Now - what happens, if you replay a wrong cylinder on a business machine? The recorder-reproducer carriage is driven by a spindle, independently of any existing grooves on a cylinder. Thus in average every 150/(150-100)=3^rd track of a 2-minute cylinder will be repeated, and every 200/(200-150)=4^th track of a 4-minute cylinder will be skipped. In reality, since the stylus has lateral degrees of freedom, it will follow the tracks for some time and then jump a few tracks at once, backwards or forwards, respectively. Don't be fooled by drawings from Edison's patent specifications, they are not drawn to scale. A track, at a volume level limited by the requirement that it does not overlap with its neighbour (and thus risk a repeated or jumped track), is only 15 micrometers deep (size of a thin women's hair), when recorded with a cylindrical stylus of 0.5 mm diameter (pict.49). The picture demonstrates two more facts: a) only the lower 40/360=11% of the circumference of a (cylindrical) recorder stylus are used and have to be shaped properly, and b) the enormous sensitivity of the human ear.

"A business phonograph won't play Blue Amberols or gold-moulded wax cylinders"
True: As explained before, it is only the track density which causes this incompatibility. Otherwise it's ok, the mandrel diameter is ok, the stylus size is still ok.

"This phonograph has a crank - so it must be older than the electric motor machines"
Wrong: As discussed above in the beginning all phonographs were business phonographs and had electric motors, either powered by a storage battery, or by 110V DC. My 1908 business phonograph C (ref.1) had a variable rheostat on its back, accommodating any electrical power source from 220V DC down to 110V 133 cycle AC (pict.50). The first spring motor was made by Edison in 1895, almost 20 years after he invented the phonograph. Motivations for change were the messy batteries, safety concerns, and such simple things like the wish to limit phonograph parlor sessions to the time paid for. The most important reason however was that many homes just did not yet have household current installed. Household and rural electrification was far from being completed - and who would understand this better than Edison. Spring motors were used for almost all entertainment machines, but only about 4% of business machines sold in the 1910's were hand-cranked.

"My phonograph has a double-spring motor, so it plays 4 times longer than the single-spring Home"
Wrong: The motor is a double spring motor with a gearbox cloned from the contemporary Home model (the crank too is the same as for the Home). Instead of directly driving the gearing the first spring drives a second spring, that then drives the gearing, suggesting the number of turns to windup both springs multiply, compared to one. Think again and find out that they add, unlike transmission ratios in the gearing itself, which multiply. The motor has a unique feature, a wound-down alarm bell (pict.s 34-37), that rings 3 times when the motor needs rewinding. It works as follows: when the motor is wound up, the second spring barrel follows the first one with half the number of turns. A little pin on the first barrel engages a cogwheel on the second barrel each time it passes. Each time the cogwheel is advanced, 3 teeths on a comb are moved nearer to the barrel center so they get out of reach to engage a clapper of the bell. When the motor unwinds, the pin turns the cogwheel in the opposite direction, causing the teeth to move further away from the barrel and eventually strike the bell's clapper 3 times in a row, and repeating the alarm again when the two barrels pass by eachother the next time, until both springs are discharged.

Here are the specifications:

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