POPULAR MISCELLANY 



835 



ing over the aperture a film of soapsuds. 

 By turning the wrist, the angle made with 

 the direction of the light may be readily 

 adjusted ; a motion of the elbow alters the 

 distance from the mouth, and the tension of 

 the film can be exactly regulated by moving 

 the thumb and finger. On singing or speak- 

 ing to the film when in proper tension, beau- 

 tiful figures appear, which may be reflected 

 direct from the film on a screen. The ex- 

 periment is extremely curious and interest- 

 ing. 



George Bidder, the " Calculating Boy." 



— There died lately in England a man of 

 prodigious arithmetical power, whose men- 

 tal faculties would aiFord matter for pro- 

 found research to the psychologist. George 

 Bidder made his mark in early life as a 

 " calculating boy " ; but in him one over- 

 grown faculty did not eclipse all the other 

 mental powers, for throughout life (he died 

 aged seventy-two years) he evinced first-rate 

 business ability, and in fact accumulated a 

 large fortune by his own exertions. Nor did 

 his mathematical faculty decline as his other 

 powers matured ; to the last he was capable 

 of the same astonishing feats of calculation 

 which made him remarkable as a boy. In- 

 stances of his extraordinary powers are 

 given in a letter written by James Elliot, 

 Professor of Mathematics in Queen's Col- 

 lege, Liverpool, who was Bidder's fellow stu- 

 dent in Edinburgh. Of these we quote two : 

 A person might read to Bidder two series of 

 fifteen figures each, and, without seeing or 

 writing down a single figure, he could mul- 

 tiply the one by the other without error. 

 Once, while he was giving evidence before a 

 Parliamentary committee, counsel on the 

 opposite side interrupted him with, " You 

 might as well profess to tell us how many 

 gallons of water flow through Westminster 

 Bridge in an hour." " I can tell you that 

 too," was the reply, and he gave the num- 

 ber instantaneously. 



Certain interesting facts are mentioned 

 with regard to the possession of the same 

 or similar powers by members of Bidder's 

 family. His eldest son, who is a successful 

 barrister, can play two games of chess si- 

 multaneously without seeing the board. Like 

 his father, he can multiply fifteen figures 

 by fifteen without seeing them, but by a 



pecuhar process. One of the grandsons 

 showed a very marked degree of mechani- 

 cal ingenuity. Even the granddaughters 

 possess extraordinary powers of calculation. 

 George Bidder's elder brother, a Unitarian 

 minister, was not remarkable as an arith- 

 metician, but had an extraordinary memory 

 for Bible texts, and could quote almost any 

 text in the Bible, and give chapter and 

 verse. Another brother was an excellent 

 mathematician, and was actuary of a great 

 life-insurance company. 



Pernvian Antiquities. — In an article on 

 Peruvian antiquities, published in the " Kan- 

 sas City Review of Science and Industry," 

 Dr. E. R. Heath gives an interesting account 

 of the vast wealth of ruins with which the 

 land of the Incas is overstrewed. Go where 

 you will m Peru, and relics of the past meet 

 your eye either in ruined walls, watercourses, 

 terraces, or extensive areas covered with 

 broken pottery. Dr. Heath takes as an 

 illustrative instance the Jequetepeque Val- 

 ley. Here the bottom-lands of the river 

 are from two to three miles in width, with 

 a southern sloping bank, and the northern 

 a perpendicular one nearly eighty feet high. 

 Beside the southern bank, near the point 

 where the river empties into the sea, is an 

 elevated platform, one quarter of a mile 

 square and forty feet high, all of adobe. A 

 wall, fifty feet wide, connects it with another 

 distant a few hundred yards, which is 150 

 feet high, 200 feet across the top, and 500 

 feet at the base, and nearly square. This 

 latter structure was built in sections or 

 rooms ten feet square at the base, six feet 

 at the top, and about eight feet high. These 

 rooms were afterward filled with adobes, 

 then plastered on the outside with mud and 

 washed in colors. All the Peruvian mounds 

 of this class have on the north side an in- 

 cline as a means of access. On the north 

 side of the river, on the top of the bluff, 

 are the ruins of a walled city two miles wide 

 by six miles long. In following the river 

 to the mountains you pass ruin after ruin, 

 one artificial mound (huaca) after another. 

 At Tolon, a town at the base of the moun. 

 tains, the valley is crossed by walls of bowl- 

 ders and cobble-stones, ten, eight, and six 

 feet high, one foot to eighteen inches wide 

 at the top and two to three feet at the base, 



