Difficulty of determining the Laws which govern the Strength of Materials.--Forces tending to separate the Parts of a Solid.--Laws by which Solids resist Compression.--Euler’s theory.--Transverse Strength of Solids.--Strength diminished by the Increase of Height. --Lateral or Transverse Strain.--Limits of Magnitude.--Relative Strength of small Animals greater than large ones. 272 CHAP. XXI. ON BALANCES AND PENDULUMS. Weight.--Time.--The Balance.--Fulcrum.--Centre of Gravity of.-- Sensibility of.--Positions of the Fulcrum.--Beam variously constructed.--Troughton’s Balance.--Robinson’s Balance.--Kater’s Balance.--Method of adjusting a Balance.--Use of it.--Precautions necessary.--Of Weights.--Adjustment of.--Dr. Black’s Balance.-- Steelyard.--Roman Statera or Steelyard.--Convenience of.--C. Paul’s Steelyard.--Chinese Steelyard.--Danish Balance.--Bent Lever Balance. --Brady’s Balance.--Weighing Machine for Turnpike Roads.--Instruments for Weighing by means of a Spring.--Spring Steelyard.--Salter’s Spring Balance.--Marriott’s Dial Weighing Machine.--Dynamometer.-- Compensation Pendulums.--Barton’s Gridiron Pendulum.--Table of linear Expansion.--Second Table.--Harrison’s Pendulum.--Troughton’s Pendulum.--Benzenberg’s Pendulum.--Ward’s Compensation Pendulum.-- Compensation Tube of Julien le Roy.--Deparcieux’s Compensation.-- Kater’s Pendulum.--Reed’s Pendulum.--Ellicott’s Pendulum.--Mercurial Pendulum.--Graham’s Pendulum.--Compensation Pendulum of Wood and Lead.--Smeaton’s Pendulum.--Brown’s Mode of Adjustment. 278 THE ELEMENTS OF MECHANICS. CHAP. I. PROPERTIES OF MATTER--MAGNITUDE--IMPENETRABILITY--FIGURE--FORCE.