<s id="A18-1.34.01">[34] Let a circular disc or a pulley be mobile on an axle around the center <a>; let its diameter, the line <bg>, be parallel to the horizon.</s>
<s id="A18-1.34.02">Let us now suspend at points <b> and <g> two strings, namely <bd> and <ge>, on which two equal weights are hanging, then we see that the pulley does not incline to any side, because the two weights are equal and the two spaces from the point of suspension <a> are equal.</s>
<s id="A18-1.34.03">Let now the weight at point <d> be greater than the one at <e>, then we see that the pulley inclines towards <b> and point <b> drops together with the weight.</s>
<s id="A18-1.34.04">Now we have to learn, in what place the greater weight <d>, when it drops, comes to rest.</s>
<s id="A18-1.34.05">Let us therefore lower point <b> and let it come to <z> and let then the string <bd> be with string <zh>, so the weight comes to a stand still.</s>
<s id="A18-1.34.06">We now see that string <ge> winds itself around the rim of the pulley and that it hangs on the weight from point <g>, because its wound-up part no longer hangs down.</s>
<s id="A18-1.34.07">If we now extend <zh> to point <q>, then, because the two weights are in balance, the ratio of the one weight to the other is in the same (inverse) ratio of the distance of point <a> from the strings and it is like <ag> is to <aq>, so the load at <h> is to the load at <e>.</s>
<s id="A18-1.34.08">If we make the ratio of <ga> to <aq> equal to the (inverse) ratio of load to load and shift points <b>, <g> towards <zq> at a right angle, then we see that the pulley has moved from point <b> to point <z> and is at rest.The same observation is also true for other weights.</s>
<s id="A18-1.34.09">Thus according to this point of view every load can keep the balance of a load that is smaller than itself.</s>
<s id="A18-1.34.10">This may be enough for the first book of the introduction to mechanics.</s>
<s id="A18-1.34.11">In the following we are going to deal with the five powers by means of which loads are moved, explain what they are based on and how the natural effect in them occurs.</s>
<s id="A18-1.34.12">Furthermore we shall speak of other things that are of great benefit in the lifting and carrying of the loads.</s>
<s id="A18-1.34.13">End of the first book of Heron's writings on the lifting of heavy objects.</s>
