Of the first type may be mentioned the Euler, which is a modification of the Voisin; the Otto, which embodies the H. Farman principles; the D.F.W. (Deutsche Flüggen Werk); some of these are practically H. and M. Farman biplanes. They also include a rapid type, called Mars biplanes, in which the main surfaces are shaped like those of the famous Nieuport machine. Amongst the more distinctive machines are THE AVIATIK BIPLANE. This is one of the most noticeable of German machines. A special feature is the space provided in the front part of the fuselage, which gives the observer every opportunity of free movement for scouting, writing, photographing, and throwing bombs. The vital parts and front are well fortified with a metallic “capot,” and the rest of the fuselage is also armoured. The rapid erection and dismantling of this machine has been especially well planned. The supporting surface consists of two planes of unequal dimensions, the upper one being the larger. Each is divided into two sections fixed independently on the fuselage. The planes are coated with a liquid to render them incombustible. The longitudinal stability is assured by a fixed plane prolonged by a rudder for controlling the vertical movements. Two large “ailerons” at the back of the upper planes are provided for lateral stability. [Illustration: [_Topical Press._ A RUMPLER MONOPLANE (A TAUBE), showing the distinctive bird shape so affected by the German monoplane makers.] Steering is effected by a vertical rudder placed between the two portions of the horizontal plane rudder. The dimensions of one type of the Aviatik can be seen in the table of types of German aëroplanes. THE RUMPLER MONOPLANE. In this, as in all the Taube flying machines, the wings are in the shape of a dove or pigeon. The end of the wings are flexible. The stability of the apparatus is assured both by the shape of the wings and their flexibility. It is at once a combination of the inherent stability type and that depending on the warping of surfaces; the advisability of blending the principles is one practice alone can decide. In some of the Rumpler monoplanes, instead of the ends of the wings being flexible, there are “ailerons” attached. THE RUMPLER BIPLANE. This biplane with the Aviatik is remarkable for the amount of space provided for pilot and observer. The fuselage is protected in front with aluminium. The upper plane is not made to join in the centre, as in most German machines; instead, there is a short immovable central plane, which is permanently attached to the fuselage by four tubes; to the ends of this central plane, on either side, the other planes are fixed. THE ALBATROSS.