Apparatus to Accompany Tyndall’s “Lessons in Electricity”
Thomas B. Greenslade, Jr.
Kenyon College, Gambier, Ohio 43022
The Royal Institution’s series of Christmas Lectures for young people and the general public has been presented every year since 1825, with the exception of the war years 1939-1942. The first lecture was on “Natural Philosophy” by John Millington, who later became the first Professor of Natural Philosophy at the University of Mississippi in 1848. (Ref. 1) The most prolific lecturer was Michael Faraday, who presented nineteen lecture series and most of us are familiar with the book that came from his lectures on, “The Chemical History of a Candle.” John Tyndall (1820-1893) gave eleven lecture series (Ref. 2), and his book, “Lessons in Electricity”, was drawn from his presentations on Experimental Electricity during the 1875-76 Christmas season. (Ref. 3)
The title to this book is somewhat misleading: it is wholly concerned with static electricity, although by the middle 1870s electro-chemical cells, generators, induction coils, ammeters and voltmeters, electric motors and other applications of current electricity were well known. As such, it represents a remarkably complete discussion of the delightful, and in many cases, literally illuminating, demonstrations that so delighted our Victorian ancestors. The only contemporary book giving such details is G.W. Francis’ 1854 book, “Electrical Experiments” (Ref. 4).
Unlike the other books by Tyndall, and he published eighteen of them, plus numerous articles, “Lessons in Electricity” is clearly aimed at the younger market. In the preface, Tyndall remarks that “I had heard doubts expressed as to the value of Science-teaching in the schools, and I had heard objections urged on the score of the expensiveness of apparatus. Both doubts and objections would, I considered, be most practically met by showing what could be done, in the way of discipline and instruction, by experimental lessons involving the use of apparatus so simple and inexpensive as to be within everybody’s reach.” Tyndall had a silent author, his assistant Mr. Cottrell, who appears in sentences such as, “Mr. Cottrell, who has been working so hard for you and me” to develop inexpensive versions of the apparatus sold by apparatus suppliers.
Bound into the back of the 1888 American edition of “Lessons in Electricity” is a list of twenty pieces of apparatus, “necessary to illustrate this book” that could be bought for $66 to enable the young experimenter to reproduce Tyndall’s experiments. These were offered for sale by the New York firm of J.H. Berge, “Manufacturers of Electrical and Philosophical Apparatus of best quality and latest improved designs.” The company, founded in 1850, is still in operation in South Plainfield, New Jersey, but now appears to deal with all sorts of apparatus for all scientific fields save physics. I must take exception to the list, as it is not inclusive, and starts out with “One latest Improved Holtz Electrical Induction Machine” with a twelve inch plate, etc. This is not discussed in Tyndall’s book. Furthermore, there is no electrophorus, a key piece of electrostatic apparatus.
On the other hand, the 1886 catalogue of the Curt W. Meyer Company of 347 Fourth Avenue in New York City has a set of apparatus that is congruent with the experiments illustrated in Tyndall’s book. Meyer notes, two years before Berge, that this is “the only American apparatus designed to accompany” the book. The complete set of apparatus is shown in Fig. 1, and is listed at $65 with the box and a copy of Tyndall included. So far I have located three of the major pieces of apparatus. Many of the other items in the set are consumables, such as pack thread, needles, fragments of paper, squares of flannel and silk, foolscap paper, etc.
The most complex apparatus is the small cylinder electrostatic machine in Fig. 2; the instrument is in the Greenslade Collection. In Fig. 1 its number is 34, and it is the most expensive item in the set, costing $8.00. The machine is constructed primarily of wood, with the metal pins that pick off the charge set into a block with rounded corners (to prevent current leakage) that has been covered with tinfoil. The separation of charge is effected by a “rubber” that is faced with leather and held by a spring against the surface of the glass cylinder.
The book’s illustration of the cylinder machine leaves no doubt that the instrument in Fig. 2 was derived from it. The accompanying text notes that, “Mr. Cottrell has constructed for these Lessons the small cylinder machine shown in Fig. 26. The glass cylinder is about 7 inches long and 4 inches in diameter: its cost is eighteen pence. Through the cylinder passes tightly, as an axis, a piece of lath, rendered secure by sealing wax where it enters and where it quits the cylinder. G is a glass rod supporting the conductor C, which is a piece of lath coated with tinfoil. Into this lath is driven the series of pin point, P,P. The rubber R is seen at the further side of the cylinder, supported by the upright lath R’, and caused to press against the glass. S’ is a flap of silk attached to the rubber. When the handle is turned sparks may be taken, or a Leyden jar charged at the knob c.” (Ref. 5)
The other device in my collection is shown in Fig. 3. This goes by various names: in the list accompanying Fig. 1 it is called a Lieden jar with movable coatings, and its number is 48, in the 20th century it was commonly called a dissectible condenser, and in the 21st century it has essentially disappeared. The original cost was $1.50. The instrument in the Greenslade Collection is missing the glass cup that fits into the outer metal shell and into which the inner shell nestles. This is placed on an electrical insulator and charged in the usual fashion using the output of the electrostatic machine, and, if it is untouched and in a dry climate, will keep its charge for a long time. It is dissected by lifting the inner conductor out with a non-conducting rod and placing it on an insulated stand. The glass dielectric cup is removed, and placed on another insulating stand, leaving the outer conductor sitting alone on its own insulator. You can then show that the amount of charge on either conductor is very small, while small bits of paper are attracted to the glass, showing that it is electrified. When the condenser is reassembled, it is found to be fully charged. This somewhat mystifying demonstration was invented by Benjamin Franklin in 1747-48.
Figure 4, #35 in the first figure, is a conical electrical conductor ($1.00). In the fall of 2011 I found it in the physics collection at the University of Maine in Orono, and can only assume that at one time the physics cabinet had the entire Meyer set. It is made of metal and intended to be placed on an insulating stand. Tyndall discusses how an electroscope (# 18) can be used to check the amount of electric fluid that accumulates at various places on a charge conductor; the sharp point on the conical conductor is a place with a high concentration of electricity.
Many of the pieces of apparatus in Fig. 1 are ephemeral, but I would hope someday to locate the Electrophorous (#33, $3.50), Cottrell’s Rubber (#49, $1.50, a clever device for charging a rod) and the Long Cylindrical Conductor (#19, $4.00). The Electric Mill (#39, $0.50), from another maker, is shown in Fig. 5, and spins rapidly as the charge on it leaks off the sharp points of the wires.
The Meyer catalogue shows other sets of physics apparatus, including Prof. Curt W. Meyer’s “Student’s Electrical Cabinet” in Fig. 6. This was designed as a Christmas present – a Holiday Scientific Gift. The Meyer catalogue quotes the New York Times, which, in reviewing the set about 1880, noted that few holiday gifts are intended for instruction. “It is quite possible, however, to construct certain objects by which a lad can not only be made happy in their positions, but which at the same time may become a prominent feature in his education. Prof. Curt W. Meyer, of this city, presents for the holiday season a very perfect set of electrical instruments. In a convenient box [not more than a foot square] may be bought a compact electrical plate machine, perfectly capable of generating electricity, with electrical orrery, cannon, bells, pith ball electrometer, Leyden jar, head of Medusa, and a Geissler or Vacuum tube, with other apparatus.” The set was accompanied by Meyer’s 25 page book, “Elementary Guide to Electricity” that otherwise sold for a quarter.
A common lecture demonstration today in physics courses is electrifying a pickle. Nails thrust into the end of a big kosher dill are connected to the output of an auto-transformer, and the voltage turned up until the pickle starts to glow yellow. Looking at the yellow light through a spectroscope reveals the presence of the sodium D-lines; the pickle is saturated with sodium chloride. Tyndall takes this delightful demonstration back to Cadogan Morgan, who, in 1785, passed electricity from a Leiden jar through wood, an ivory billiard ball, an orange and an apple. The text shows a lemon on a stand with electrodes top and bottom, with the comment that this produced “a spheroid of brilliant golden light.” He also mentions that a row of eggs in a glass cylinder is brilliantly illuminated at the passage of every spark from a Leiden jar. In my own collection is an egg illuminator (Fig. 7) made ca. 1870 by Ritchie of Boston. I have been wary of trying out the demonstration, but Sean Corron of Maryland has done it, using a sign transformer in place of the Leiden jar, and reported to me that “when the current passes through the eggshell, it glows an eerie orange. To prove that the electricity was passing through the shell and not the egg, I drilled two small holes and forced the egg out of one hole by blowing through the other. The evacuated egg glows the same as one complete. In fact, the empty egg is more reliable.” (Ref. 6)
There are a number of homilies directed toward the young experimenter. Typical is: “More than half the value of your present labour consists in arranging each experiment in thought before it is realized in fact; and more than half of the delight of our work will consist in observing the verification of what you have foreseen and predicted.” (Ref. 7)
I would enjoy writing a review of Tyndall’s book for the physics teaching journals, perhaps to revive interest in electrostatics. The subject has shrunk down to a maximum of one lecture on the college level, with the lecturer perhaps hoping that the high school teacher has covered the topic more thoroughly. There are few laboratory courses on this level that have space for electrostatics, despite the fact that the subject typically appears in the middle of the academic year, which, in North America, is a time of heated buildings with low humidity, just perfect to make the experiments snap and crackle.
- Thomas B. Greenslade, Jr., “Visits to Apparatus Collections V: The University of Mississippi”, Rittenhouse, 19, 16-26 (2005).
2. The Tyndall Christmas lectures at the Royal Institution are:
1861 … Light
1865 … Sound
1867 … Heat and Cold
1869 … Light
1871 … Ice, Water, Vapour and Air
1873 … The Motion and Sensation of Sound
1875 … Experimental Electricity
1877 … Heat, Visible and Invisible
1879 … Water and Air
1882 … Light and the Eye
1884 … The Sources of Electricity
A number of these lecture series were issued as books; in North America, these were published by Appleton of New York in their familiar rust-red bindings. Perhaps the best of these are, “Heat, Considered as a Mode of Motion” (1863) and “Sound” (1867), both of which came out in various revised editions in later years.
3. John Tyndall, Lesson in Electricity at the Royal Institution 1875-6, (D. Appleton and Company, New York, 1888).
4. George W. Francis, Electrical Experiments, (1854). This was reprinted in 2005, with additional material, by Oleg Jefimenko, the late Professor of Physics at West Virginia University and expert on electrostatics. (Electret Scientific Company, P.O. Box 4132, Star City, West Virginia 26504).
5. Reference 3, pg. 55.
6. Private communication.
7. Reference 3, pg. 50.