Inclined Plane
   "When roads are to be made over steep hills, they are sometimes constructed around the hill, like the thread of a screw , or in a winding manner as shown in the [figure at the right]. The road from Callao to Lima, in South America, is said to be one of the longest and best-made inclined planes in the world. It is six miles in length, and the total rise is 511 feet." -- from J. Dorman Steele, Fourteen Weeks in Natural Philosophy, New York, A. S. Barnes, 1869), pp 93-94, 

   The relationship between the inclined plane and the helix is demonstrated by the  paper model of a helix at the University of Mississippi. 

   The inclined plane is a basic building block of introductory physics. Perhaps present-day students consider it dull and boring because they do not have the opportunity to do experiments with it.

   This inclined plane in the Amherst College collection  is by Ducretet of Paris and is 40 cm high. It was bought as a replacement after all of the original Amherst apparatus was destroyed by the burning of the original Walker Hall on March 28, 1882.

   The block is not original. When new, the body on the inclined plane was a roller, as shown in the picture below.

 

   At the right is an inclined plane offered at an Ebay auction in late October 2000. The apparatus is by the Ziegler Electric Company of Boston, Massachusetts. The 1912 catalogue of the L. E. Knott Apparatus Co. of Boston lists this inclined plane at $4.45, and calls it Hall's Inclined Plane Apparatus. The Boston connection is unmistakable: this apparatus was designed for by Edwin Hall of Harvard, known for the Hall Effect, and the seminal list of 40 experiments suggested for entrance to Harvard. The apparatus is described in Hall, Edwin H., and Bergin, Joseph Y., A Textbook of Physics, largely experimental, on the basis of the Harvard College "Descriptive List of Elementary Physical Experiments" (Henry Holt and Company, New York, 1892) copyright 1891.
    The experiment on inclined planes in Millikan and Gale's 1906 book, A Laboratory Course in Physics for Secondary Schools tells how this apparatus was used. The roller, of known weight, removes most of the friction from the system. The angle is adjusted, and weights added to the end of the cord until the system balanced. The roller was run down the plane a known distance, and the amount by which the hanging weight rose was measured. The product of the weight and the distance for each body should thus be the same.
 The markings on this inclined plane at the Virginia Military Academy in Lexington, Kentucky give clues to the import trade in scientific instruments. In the center of the plane is the marking "W. G. Pye & Co./Makers/Cambridge". On the top are the words "Imported by Arthur H. Thomas Co., Phila.", and on the bottom is marked "Ziegler Elec. Co., Boston".

   The 1911 Pye catalogue shows a much plainer piece of apparatus, suggesting that the VMI apparatus is older.

   This inclined plane is listed in Leland A. Browns invaluable book, Early Philosophical Apparatus at Transylvania University, published in 1959.

   He quotes an early textbook, "Place a block on an inclined plane, whose angle can be varied, and then find the relative friction in different cases, by the largest inclination at which it will prevent the block from sliding."

   We still find the angle of repose today for a block lying on a surface. The tangent of the angle of repose is the coefficient of friction between the two surfaces. A block which does not move until the plane is tilted up at an angle of 45 degrees thus has a coefficient of friction of 1.00, relative to the material of the plane.

   The inclined plate at the left is in the Garland Collection of Classical Physics Apparatus at Vanderbilt University. 

   The plane itself is made of glass, and there is an auxiliary pulley at the upper end of the plane to keep the cord attached to [missing] sliding body parallel to the plane. The angle of the plane is adjusted by turning the crank.

   Unfortunately, this unusual and interesting inclined plane is unmarked. It probably dates from about 1875, when Vanderbilt built up its collection of apparatus for natural philosophy.

   This inclined plane by Queen is at the University of Cincinnati. The pulley seems to be adjustable to allow blocks of different thicknesses to be used while still allowing the cord to be parallel to the plane. 
 The small, unmarked inclined plane at the left is at Colby College in Waterville, Maine. 
   At the right is an inclined plane by Lerebours et Secretan of Paris that is listed at 140 francs (about $28) in the 1853 catalogue. 

   The surface is made of glass, and at one time the base contained a bubble-level. 

   The apparatus is on display at the University Museum of the University of Mississippi in Oxford. It is part of the Millington/Barnard collection and was almost certain bought by Frederick A.P. Barnard in the second half of the 1850s.

   This unmarked inclined plane is at the physics department of the University of Texas in Austin.
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