Section I. [Equation 3]

the same would be found in the interior of the gas, increased by the momentum original: "Bewegungsmoment"; in this context, it refers to the quantity of motion or momentum transferred during impact which corresponds to the velocities with which these molecules move away from the surface back into the interior of the gas.

§ 3. Number of collisions against the wall.

We first single out from all the molecules only those for which the magnitude of the velocity $c$ lies between $c$ and $c + dc$, the angle $\vartheta$ the Greek letter theta, which its direction forms with the normal $N$ a line perpendicular to the surface erected outwards from the surface $DE$, lies between $\vartheta$ and $\vartheta + d\vartheta$, and the angle $ε$ the Greek letter epsilon between a plane normal to $DE$ containing the direction of the velocity and a fixed plane normal to $DE$ lies between $ε$ and $ε + dε$. We shall refer to the totality of these requirements as

All molecules which satisfy them we call molecules of the specified kind, and we first ask ourselves how many molecules of the specified kind strike the surface $DE$ during a very small time interval $dt$.

Each of these molecules is to be thought of as a sphere of diameter $σ$ the Greek letter sigma and thus strikes the plane $DE$ at the moment it touches it. The centers of the specified molecules all cover nearly the same and identically directed path $c , dt$ during the time $dt$. We therefore find the number of molecules of the specified kind that strike the plane $DE$ during the time $dt$ in the following way:

At every point of the plane $DE$, we imagine it being touched by a sphere whose diameter is equal to the diameter $σ$ of a molecule. The center of all these spheres lies in a second plane with surface area $Ω$ the Greek letter Omega. Through every point of this second plane, we draw a straight line which is the same length and direction as the path $c , dt$ covered by each of the specified molecules during the time $dt$. All these straight lines fill an oblique cylinder $γ$ the Greek letter gamma with base $Ω$ and height
3)

Technical vocabulary used: momentum (Bewegungsmoment), molecules (Moleküle), velocity (Geschwindigkeit), angle (Winkel), normal (Normalen), plane (Ebene), totality/essence (Inbegriff), sphere (Kugel), diameter (Durchmesser), surface area (Flächeninhalt), cylinder (Cylinder).