190 FAL^ABLE MATHEMATTCS* 



ALGEBRA. 



*nd in algebra Tire beft method of writing algebra appears to me, likcr 

 that of arithmetic> to confift in compofing in the manner of 

 printers, with this difference, that the characters are a little 

 larger, and muft be read from left to right. This procefs has 

 the important advantage of enabling readers by fight to perufe 

 and examine the calculations. 



GEOGRAPHY. 



£afy method of There is but one method of ufing geographical maps and 

 forming tangible^ g{ be S .. [ t [ s f im ple and eafy. A fmall firing or thread is 

 palfed on all the windings or outlines of the map. The rivers 

 and mountains are difiinguiftied by different threads. Grains 

 or prominences of different fizes and fliapes are parted on the 

 and multiplying towns and other remarkable places, &c. With one of thefe 

 cy P :er < maps others may be procured by the prefs, in which the out- 



lines will be railed into relief. 



MUSIC AND BOOKS. 



Mufk book*. Citizen Haiiy has compofed mulic books for the ufe of the 



eftablifhmeut of the 'Unitize Vingts at Paris, the characters of 

 which project, or are emboffed : this method is without doubt 

 ufeful, but it is fcarcely applicable but to great foundations. 



WRITING. 



Writing on pa- Citizen Hauy's method confifts in ufing an iron pen, the 



ftiteiil^iK!!? P oint of which is not f P lit » h f writing without ink and pref- : 

 the protubc- ling on a ftrong paper, the blind man produces a character in 

 ranee. relief, which he can immediately read by pafling his fingers 



over the projecting characters on the oppofite fide of the 

 paper, in the contrary direction. This relief is fufficient, pro^ 

 vided a foft furface be placed under the paper, fuch as lea- 

 ther, blotting paper, &c 

 Frame for writ- In order to write in a ftraight line, a frame is put on the 

 wig ftraight. paper, having a number of brafs wires acrofs, parallel to the 

 direction of the writing, at the diftance of about three quarters 

 of an inch. 



His method of writing in relief has this advantage, that the 

 blind can read what they have written, after a little practice ; 



but 





