COXMUXICATION BY SIGNALS. 32; 



and ^ = 20—10-3;^; hence p = 3; c— 12; /=20; put 

 p=3; n=z5; then cr: 20; t=12 by Cor. 2; the former 

 of which is the dodccaedron, the latter the icosacdron; and 

 s = 30 in both (by Cor. 2.) 



Prop. 7th. The sum of the plane angles bounding the Prop. 7. 

 solid angles of a regular body r: 8 «jt?— 16p-i~2/> -j-2 ;z — ??/;. 

 For the sum of the plane angles belonging to each face of! Dcmonstr. 

 the body =2 w — 4 (Euclid 32.1) : but there are c faces; 

 therefore the whole sum — 2n — 4xc; audt=: 4})~-2p-\-2H 

 ~np; therefore &c. Q. E. D. 



II. 



Invcnfioji of a Homograph, or Method of Com)nurrication 

 by Signals.) on Sea or Land, Bij Lieutenant James 

 Spratt, of the Royal Navy *. 



SIR, , ■ 



ITH this you will receive a truly ingenious invention Anecdote of 

 of Lieut James Spratt, of the Royal Navy. This gallant !|,'^^^^^f.^';' "^ 

 officer, in the glorious action of the combined fleet' at Tra- 

 falgar, on the 21st of October, 1805, was on board his 

 Majesty's ship Defiance. When engaged within pistol shot 

 with a French eighty-gun ship called I'Aigle, he plunged 

 into the sea, swam to the enemy's stern, and entered the 

 gun-room port alone, made his way courageously through 

 the different decks, and succeeded in mounting the enemy's 

 poop, where placing his hat on the poial of his cutlass, he 

 called out to his men to join him. In attempting to haul 

 dpvvn the French colours, he was attacked by several of 

 their grenadiers, whom he repulsed Mith success. He was 

 soon followed by several of our jolly tars, and in tiie act of 

 saving the life of aPVench officer who cried out for quarter, 

 a musket Avas levelled by a Frenchman at his own breast, 

 which he fortunately struck downwards^ but his leg was 



* Transact, of the Society of Arts, vol xxvii, p 13:3. The sil- 

 yer medal was voted to Lieut. Spralt far this iiiveniion. 



fraptared 



