Compressores Dakin in duo genera dividuntur: genus reciprocum et genus hermeticum, compressor reciprocus maxime compositus ex domo, crankshaft, virga connectens, bracteae valvae pistonae collectae, sigillum integrum, oleum sentinam, capacitas regulator, oleum colum, suctus et exhauriunt. valvae clausae et valvae gasket etc. compressio fit ex reciprocis motibus pistonis in cylindrici, valvae gasi in et extra cylindrici moderante.