CALCULATING MACHINES 



1049 



CALCUTTA 



electric furnace. Its chief use is in making 

 acetylene gas.. The process is more fully ex- 

 plained in the article ACETYLENE. 



CALCULATING MACHINES, machines for 

 performing various arithmetical operations, in- 

 cluding addition, subtraction, multiplication 

 and division. These are made in many pat- 

 terns, the simplest of which is an adding ma- 

 chine only, like the fare register on a street 

 car, which adds but one unit at a time. This 

 contains a series of wheels, usually three, each 

 of which bears numbers from to 9. When 

 the cord which operates the register is pulled 

 the wheel respresenting units moves one step, 

 so as to mark the next higher number. In 

 making a complete revolution this wheel regis- 

 ters ten times, but as the zero appears in the 

 units column, the wheel which represents the 

 tens column is moved forward one figure. 

 Every time the zero in the units column ap- 

 pears in the indicator a small ratchet catches 

 the tens wheel and pulls it forward one figure. 

 When the tens column shows the zero, exactly 

 the same process takes place in the hundreds 

 column. 



The typical adding machine used in business 

 to-day is based on the same principle as the 

 fare register. Instead of waiting for the figures 

 in each column to appear, the adding machine 

 may be operated by keys, like a typewriter. 

 For example, to add 350 and 638: the keys, 

 3 in the hundreds column, 5 in the tens and 

 in the units, must be pushed down like the 

 letters on a typewriter; the machine records 

 them when the operator turns a crank or lever ; 

 the number 638 is picked out in the same way, 

 and then by another turn of the lever the 

 machine adds the two numbers at one opera- 

 tion. The process is exactly like that on street 

 car registers, when the register reads 9 or 19 

 or 29, and another fare is rung up; instead of 

 adding one figure or one column at a time, the 

 machine adds three, four or more by a com- 

 plicated system of interlocking wheels and 

 ratchets. The cash register (which see) is 

 merely an adding machine of a special form. 



On the more complicated forms of calcu- 

 lating machines it is possible not only to add, 

 but also to subtract, multiply and divide. On 

 the simplest machines multiplication is merely 

 repeated addition; on the earliest multiplica- 

 tion machine, to multiply 87 by 5 required 

 four turns of a crank, each turn merely adding 

 87 to the preceding number. The newest ma- 

 chines are much more complicated, but operate 

 more simply, one or two turns of a crank or 



pressures on a button being sufficient for almost 

 any problem. Machines are now constructed 

 to figure discounts and interest. See, also, 

 ABACUS; SLIDE RULE. 



CALCULUS , kal ' ku lus, the highest branch 

 of mathematics, studied only in colleges and 

 universities after a thorough preparation in 

 algebra, geometry and trigonometry. It deals 

 with the projectives of variable quantities and 

 with their rate of change. The two problems 

 below are given to indicate briefly the char- 

 acter of the work in calculus. The first is in 

 the practical field of mechanics, the second a 

 theoretical problem in astronomy: 



A ball is fired up a hill whose inclination is 

 15 ; the inclination of the piece is 45, and the 

 velocity of the projectile is 500 ft. per sec. ; find 

 the time of flight before it strikes the hill, the 

 path made by the ball, and the distance of the 

 place where it falls from the point of projection. 



A particle describes an ellipse under an at- 

 traction always directed to one of the foci ; it is 

 required to find the law of attraction, the veloc- 

 ity and the periodic time. 



CALCUTTA, kal kut'a, called by the Hindus 

 KALI GHATA, meaning "the landing place lead- 

 ing to the temple of the goddess Kali." It is 

 a city of temples and palaces and, next to 

 London, is the most populous of all the cities 

 of the British 

 Empire. Capital 

 of the presidency 

 of Bengal, and 

 until 1912 the 

 capital of the 

 great Indian Em- 

 pire, it stands on 

 the left bank of 

 the Hooghly, an 

 arm of the sacred 

 River Ganges, 

 eighty-six miles 

 from the sea. By 

 mail routes Calcutta is 11,120 miles from New 

 York; from London to Calcutta is 7,400 miles. 

 Like most Oriental cities, Calcutta is divided 

 into two parts, forming practically two cities. 

 One is modern and occupied by Europeans ; this 

 section has broad, well-kept streets, fine resi- 

 dences and many beautiful public buildings. 

 The other, the native quarter, has narrow, 

 crooked streets, squalid houses, and nothing but 

 the brilliant coloring affected by the natives in 

 their dress and ornaments to relieve the drab 

 monotony of dirt. 



Commerce. From a commercial point of 

 view the city is admirably situated, having at 



LOCATION MAP 



