Yes, this is a four cylinder which has been constructed as well by Daimler and -most of all- by Maybach (at the disused hotel Hermann). No, it is a very early model but it is not the first four cylinder in-line engine of the world. This exists since 1890 already and, just like the depicted one, is not meant for road vehicles but for boats, but installing this engine takes four more years.
If you take a closer look you will actually see two in-line double cylinders. One was obviously not yet able to cast a four-cylinders- in-line. At least the shafts are of one piece, at least the camshaft. It is arranged horizontally at the bottom and is not unlike today's. The pushrods have roller bearings above and below the cams by means of which they are moved up and down. Not quite clear is the necessary form end of the drive front (on the right).
Absolutely common by that time, only the exhaust valves are controlled by cams, those in the intake by engine vacuum (setback principle). Interesting the luxurious and nice tank and carburettor arrangement. Visible below (preferably in the front view) is the clutch. Two bevel wheels with wooden layer are simultaneously brought in contact with one at the engine exit and one at the gearbox entrance (not obviously) by axile movement and so the torque is transferred. 01/10