THE ART OF COMPUTATION, DESIGNED TO TEACH Practical Methods of Reckoning WITH ACCURACY AND RAPIDITY. BY DAVID WHITE GOODRICH, LATE LIGHTNING CALCULATOR, ERIE RAILWAY. THIRD EDITION: REVISED AND ENLARGED. NEW YORK: D. W. GOODRICH & CO., PUBLISHERS, 443 AND 445 BROADWAY. 1873. Entered according to act of Congress, in the year 1873, by D. W. GOODRICH, In the Office of the Librarian of Congress, at Washington. LANGE, LITTLE & HILLMAN, PRINTERS, ELECTROTYPERS AND STEREOTYPERS, 108 TO 114 WOOSTER STREET, N. Y. MOST authors agree that Arithmetic is the science of numbers, and the art of computation. Unfortunately, they also agree in teaching it as a science, and neglecting it as an art. Addition, Subtraction, Multiplication, and Division, are admitted to be the fundamental rules; yet they are allowed barely space enough to show how they may be performed -not how to perform them quickest and surest. Instead of drilling the pupil upon these operations till the most difficult problems are as easy to him as his alphabet, they give him a score of examples to do in the most elementary manner, and then hurry him on to puzzle him with questions never entering into the practical business of life-relating that an exceedingly ill-bred individual, being asked the hour by a man anxious to catch an express train, replied that, if the time from sunset to sunrise were divided by the time from noon to midnight, and due allowance made for the precession of the equinoxes, in forty-three minutes, fourteen and oneseventh seconds, the hands of the clock would be at right angles; or inquiring how many pounds of brown sugar at nine cents a pound must be mixed with thirteen pounds of coffee at twenty-nine cents a pound to make seventeen pounds of tea worth seventy-three cents a pound. The result is well known to teachers and to examiners. Classes that can explain cube root by geometrical blocks or algebraical formulæ, fail when asked to multiply the first five digits by the other four. Pupils who can discourse learnedly upon permutations and combinations, make labored and lamentable blunders in adding a ledger column. They know arithmetic as a science; they have not mastered it as an art. The author has been from his youth a practical arithmetician. He makes no claim to that abnor |