| Total differential (gcide)
 | Differential \Dif`fer*en"tial\, n. 1. (Math.) An increment, usually an indefinitely small one,
 which is given to a variable quantity.
 [1913 Webster]
 
 Note: According to the more modern writers upon the
 differential and integral calculus, if two or more
 quantities are dependent on each other, and subject to
 increments of value, their differentials need not be
 small, but are any quantities whose ratios to each
 other are the limits to which the ratios of the
 increments approximate, as these increments are reduced
 nearer and nearer to zero.
 [1913 Webster]
 
 2. A small difference in rates which competing railroad
 lines, in establishing a common tariff, allow one of their
 number to make, in order to get a fair share of the
 business. The lower rate is called a differential rate.
 Differentials are also sometimes granted to cities.
 [1913 Webster]
 
 3. (Elec.)
 (a) One of two coils of conducting wire so related to one
 another or to a magnet or armature common to both,
 that one coil produces polar action contrary to that
 of the other.
 (b) A form of conductor used for dividing and distributing
 the current to a series of electric lamps so as to
 maintain equal action in all. --Knight.
 [1913 Webster]
 
 Partial differential (Math.), the differential of a
 function of two or more variables, when only one of the
 variables receives an increment.
 
 Total differential (Math.), the differential of a function
 of two or more variables, when each of the variables
 receives an increment. The total differential of the
 function is the sum of all the partial differentials.
 [1913 Webster]
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