CHAP, vii.] VARIOUS TYPES OF STEAM-ENGINES. 



431 



We will do no more than mention the disc rotatory engine invented 

 by Bishop and constructed by Eennie; 1 since to understand its very 

 ingenious arrangements, which are difficult, however to follow, even 

 with the help of a figure, would require too long a description. We 



FIG. 303. Behrens's rotatory engine. 



will only describe the one that has been adopted in the Eussian navy, 

 for their gunboats and small screw steamers. 



The rotatory steam-engines by Behrens, of America, which was to 



1 See on this subject Sonnet's Dictionnaire des Mathtmatiques Apptiquees. 



