LINEAL MEASURES, 



Eng. Inchesv 



The most accurate standard of the yard, is that called the Parlia- 

 "^entary Standard, made by Bird in 1758, equal to 36*()003S 



On a measurement by the late Dr. Maskelyne, astronomer-royal, of 

 two French standard toises, exhibited by M. de la Lande in London, 



the one was found to be equal to 7&73^ 



And the other to .^..-....^ 76-736 



The medium 76*734 English inches for the toise of 6 teet, or 72 

 inches French, is adopted by Biot in his Astronomie Physique, 1810. 

 According to this medium proportion, one inch, foot, fathom, or toise, 

 English, is to one inch, &c. French as 1 : 1 '06575 precisely* Or, making 

 the French measure the unit, the English measure will be 0*938 of that 

 unit very nearly » 



In the end of 1801, Professor Pictet, of Geneva, carried over from 

 London to Paris a brass scale, of 49 inches in length, made by Trough- 

 ton. On a most accurate comparison of that scale, by Members of the 

 Institute, with the platina and iron standard metres^ the m^tre was 

 found to be (at the the temperature of melting ice) equal to* • • • • • • • • • 39*38270 



Which, reduced to the English rule of comparison, 62° of Fahrenheit, is 39*371 



The m^tre being the ten-millionth part of a quadrant of the meridian, 

 a sexagesimal degree of a great circle must be equal to 57*012 French 

 toises, or 60,760*54 English fathoms, equal to English miles 69*046 



The late eminent nautical mathematician Captain Mendoza y Rios 

 furnished this rule for converting Spanish into English measures, and 

 vice versa* 



From the logarithm of the number of Spanish feet, fathoms, &c. sub- 

 tract the constant logarithm 0*0384544, and the remainder will be the 

 logarithm of the corresponding number of English feet, fathoms, E. in. &c. 



Hence the Spanish foot is equal to • 10*98318 



■ vara, or yard, equal to 32*94954 



» ■ hraza, or fathom, equal to • 65*89908 



And 12 Spanish brazas are within a small trifle of 11 English faths. 



N.B.— The French hrasse contains only 5 French feet, and is therefore 

 only equal to 63*945 English inches, equal to 5 feet and nearly 4 inches 

 English. 



