George M. Hopkins (1842-1902) wrote a series of articles on demonstrating physical phenomena in the "Scientific American" during the last years of the 19th century. These were collected in a book, "Experimental Science," that was first published in 1890, with revisions in 1892 and 1902. It must have been well received, for the…

In an earlier article I argued that much of what used to be called "modern physics" stems from the intersection of two earlier technologies: high vacuum and high voltage. In this article I will discuss the induction coil, invented in the 1830s, reinvented in the second half of the 19th century, and still used today to produce the high…

Some of you may remember the 1979 television series "Connections" that was written and narrated by James Burke, a British science writer. Burke's technique was to choose a number of seemingly unrelated ideas and show how they led to developments in science and technology. This is an enjoyable business, even if some of the connections…

Ask a physics person what the name of Robert A. Millikan brings to mind, and most would immediately think of the eponymous experiments that he did with the charge on the electron in the years 1908 to 1913. A few might remember his work, starting in 1914, with the experimental determination of Planck's constant using the photoelectric effect. Few…

The Frahm resonance principle, in which resonating reeds indicate the frequency of mechanical or electrical oscillations, is a hardy perennial. In this note we will give some history, show some original apparatus, and show how it may be reproduced with relatively little effort.

In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

Discusses the discovery of frictional electrification in 1840, which was the basis of the nineteenth-century electrostatic generator. (MVL)

Summarizes Charles Wheatstone's 1843 paper introducing the Wheatstone bridge and the rheostat. (SL)

Describes experiments which could be performed on an 1860 rotating table apparatus. (CP)

Describes demonstrations used by the nineteenth century physicists to determine if two bodies oscillating at the same acoustic frequency were in phase. (GA)

Explains the idea that a half-length mirror is sufficient to view the whole length, regardless of distance. (GA)

Discusses the history of Rudolph Koenig's contribution to the development of acoustical apparatus. Contributions include the clock fork to determine absolute acoustic frequencies, a forerunner of the oscilloscope called the manometric flame, and an acoustic interference apparatus used in the Fourier synthesis of musical sounds. (MDH)

Describes several methods of executing lecture demonstrations involving the recombination of the spectrum. Groups the techniques into two general classes: bringing selected portions of the spectrum together using lenses or mirrors and blurring the colors by rapid movement or foreshortening. (JM)