NOTES. 



I. AVIATION. 



1. Helmholtz, Hermann Julius Ferdinand: a famous physicist, 

 born the 3ist of August, 1821, at Potsdam, near Berlin. He died 

 Sept. 8, 1894. 



2. Collected treatises. 



3. et il . . . metres : and floated down a gradient of 250 metres in 

 length. 



II. CHOC BRUSQUE SUIVANT LA VERTICALE. 



I. par l'interme"diaire de : by the intervention (means) of. 



VIII. TOUPIE. 

 i. tangentiellement a sa surface : in a line tangent to its surface. 



IX. TOUPIE GYROSCOPIQUE. 



1. sur elle-meme : on its own axis. 



2. prenant le dessus : and gravity becoming dominant. 



X. VELOCIPEDE. 



1. la chainette s'enroule . . . du frein: the chain shortens and 

 presses a portion more or less long of the brake on the wheel R'. 



2. on enfourche P instrument : one sits astride of the machine. 



XVI. CYLINDRE REMONTANT UN PLAN INCLINE. 



1 . pose*es de champ : put on the edge. 



2. Magasin pittoresque : a French review. 



XX. LAMPE DE DAVY. 



i. Sir Humphry Davy, the eminent natural philosopher, was born 

 December 17, 1778, at Penzance, in Cornwall (England). 



