Lancaster: American Institute of Physics, 1911. 1st Edition. BOUND FIRST EDITION OF MILLIKAN’S FIRST COMPREHENSIVE ACCOUNT OF HIS FAMOUS OIL-DROPLET EXPERIMENTS. With this experiment, Millikan established the electron as the fundamental unit of charge. Writing nearly a hundred years later, the historian of science Robert Crease observed: “Robert Millikan’s oil drop experiments can leave no-one in doubt that electrical charge is quantized and that modern physics is real, observable, and true” (Crease, Robert. Physics World, 2002, p. 19). The Nobel Prize in Physics 1923 was awarded to Robert A. Millikan "for his work on the elementary charge of electricity and on the photoelectric effect".
By modifying Wilson's cloud-chamber technique and substituting oil for water. Millikan was able to observe individual charged droplets of oil for hours at a time, measuring changes in their velocity and determining from his measurements that the electrical charge on any drop was always an integral multiple of e = 1.60 x 10-19 coulomb.
Late in 1909 Millikan greatly improved the drop method by substituting oil for water. Because of the relatively low volatility of this liquid, he could measure the rise and fall of the drops for up to four and a half hours. Spraying the chamber with radium radiation, he could change the charge on a single drop at will. His overall results decisively confirmed the integral-multiple values of the total charge.
As for the determination of e itself, Millikan found that Stoke's law was inadequate for his experimental circumstances because the size of the drops was comparable with the mean free path of the air. Using the so-called Stokes-Cunningham version of the law, which took this condition into account, by late 1910 he had computed a charge for e of 4, 891 x 10-10 e.s.u. (DSB Vol. 9 p. 396).
Not only had Millikan found the value of the charge on the electron, but he had provided convincing evidence that all electrical charge is some integer multiple of an elementary charge e, that the charge was always an integral multiple of an irreproducible value.
ALSO INCLUDED: First edition of Child's Law. "First proposed by Clement D. Child in 1911, Child's Law states that the space-charge limited current (SCLC) in a plane-parallel vacuum diode varies directly as the three-halves power of the anode voltage Va and inversely as the square of the distance d separating the cathode and the anode" (pp. 492-511). Item #810
CONDITION & DETAILS: Lancaster, American Institute of Physics. 4to. 10 x 7 inches (250 x 150mm). 645 pages. Pages 637-634 of the index at the rear missing; no papers are impacted. Ex-libris bearing only an illustrated 'Harvey Mudd College Library' plate on the pastedown; faint stamp on the rear of the title page and miniscule gilt 'Harvey Mudd College' at the foot of the spine. Tightly, cleanly, and solidly bound in brown cloth, gilt-lettered at the spine. Bright and clean throughout. Very Good ++.