Description: Pitch pool.

Caption: Kelvin demonstrated this model to his classes. At the start of every year he half filled the bowl with water and placed into it some objects that floated. He then placed a slab of wax on the water and then heavy objects such as bullets and coins on top of the wax. by the end of the year the bullets were resting on the bottom of the bowl and the corks were on the surface of the wax.

Introduction: Lord Kelvin's 'ether' was a substance, supposed to pervade the entire universe, linking all forms of energy. His theory demanded that the 'ether' required to be perfectly inelastic (stiff). He found that Scotch cobbler's wax was a good model for the 'ether'. It has the unusual property that when struck sharply or dropped from a height onto a hard surface, it shatters. But if left to stand would flow very slowly like treacle. He thought that these properties could explain how all the matter in the universe, including us, could travel through a perfectly inelastic (rigid) 'ether'.

Background: There is another version of this type of model made in about 1887 called 'the pitch glacier' (see GLAHM 113597). Although Kelvin's theories on light were ultimately proved wrong, his practice of making models, to represent physical processes, has become standard practice in all branches of science and engineering across the world.

Historical Context: Design - When: circa 1881 - Where: Glasgow, Scotland - Who: Thomson, William, Professor (1824-1907) Sir William Thomson from 1866 and Ist Baron Kelvin of Largs from 1892 better known as Lord Kelvin

Historical Context: Manufacture - When: circa 1882 - Where: Glasgow, Scotland - Who: Thomson, William, Professor (1824-1907) Sir William Thomson from 1866 and Ist Baron Kelvin of Largs from 1892 better known as Lord Kelvin

Historical Context: Used at the Gilbert Scott Buildings in lecture demonstrations in the Department of Natural Philosophy - Who: Thomson, William, Professor (1824-1907) Sir William Thomson from 1866 and Ist Baron Kelvin of Largs from 1892 better known as Lord Kelvin

Historical Context: Used in lecture demonstrations in the Department of Natural Philosophy now called the Department of Physics and Astronomy - Where: Natural Philosophy Lecture Theatre, Gilbert Scott Building, University of Glasgow, University Avenue, Glasgow, Scotland

Historical Context: Used in the Gilbert Scott B'lding by Prof. William Thomson in the Department of Natural Philosophy now called the Department of Physics and Astronomy - When: circa 1886

Historical Context: Event - "Lord Kelvin: A life in science" exhibition, Hunterian Museum, University of Glasgow. Object on display in this exhibition.