PAINTING. 521 



common ink. A book is said to be in folio, (2io), when a sheet is 

 folded into two leaves ; in quarto, (4o), when a sheet makes four 

 leaves ; in octavo, (Svo), when a sheet is folded into eight leaves ; 

 and in duodecimo, when twelve leaves are contained in one sheet. 

 Every book intended for reference, should contain a table of contents 

 at the beginning, and a copious alphabetical index at the close. 



5. The Telegraph, is a contrivance for communicating with 

 persons at a distance, by means of a system of preconcerted signals. 

 That invented by Chappe, and called by him the semaphore, or 

 signal bearer, consisted of a wooden bar, called the long indicator, 

 supported at the top of a strong mast, and capable of revolving in a 

 vertical plane, on an axle passing centrally through it. It was moved 

 by means of a cord, passing over a pulley, attached to the same axle; 

 and at each end of it were smaller arms, called indicators, attached to 

 it by an axle, and capable of turning around it, so as to take any re- 

 quired direction, by means of cords and pulleys. This apparatus, 

 since called the T telegraph, admits of about 100 different signals ; 

 each of which may be made to represent either a letter, a number, a 

 word, or a sentence. The stations are usually from five to ten miles 

 apart ; and in this way information has been conveyed at the rate of 

 more than 500 miles in a minute. 



The semaphoric telegraphs, erected by Mr. Parker, in Boston 

 Harbor, consist of tall masts, having each three moveable arms, one 

 at the top, called the indicator, and the others at different heights 

 below. Each of these arms may be placed in six different positions, 

 making a total of 216 simple combinations, which by compounding, 

 or taking them two or more at a time, may express any desirable 

 number of words or sentences. In place of these, and in correspond- 

 ence with them, there are six marine flags, of blue and white 

 differently disposed, which, with a seventh, called the conversation 

 flag, used to announce an intended conversation, constitute a Marine 

 Telegraph, of great service occasionally to ships at sea. A Tele- 

 graphic Dictionary is prepared, answering to these signals ; by means 

 of which, an intelligent person may, in a short time, be able to 

 understand the indications of the telegraph if it be visible. 



CHAPTER II. 



PAINTING. 



PAINTING, in its generic sense, including drawing, is the art of 

 representing objects on surfaces, by means of lines, shades, or colors. 

 The name is derived from the French, peindre, to paint ; and this 

 perhaps from the Latin, pingere, of the same meaning. In a more 

 limited or specific sense, painting signifies the representation of 

 objects by means of their appropriate colors : but as this cannot be 

 done without giving their outlines, which constitutes drawing, and 

 their chiaroscuro, or lights and shades, by the process of shading, 

 these latter processes are included, together with coloring, in the 

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