Papers on mechanical and physical subjects

Front matter

Cornell University Library

The original of tinis book is in the Cornell University Library.

There are no known copyright restrictions in the United States on the use of the text.

Contents

7. On the Bumting of Trees and Objects struck by Lightning . 41 — 42

An experiment showing the explosive effect of lightning to be probably due to the conversion of moisture into steam.

7a. On the Destruction of Sound by Fog and the Inertness of

Section I. — Introduction

General description of the phenomenon of thermal transpiration — correspondence of the results from plates of different coarseness when the densities of the gas are inversely as the coarseness of the plates — proof that gas is not a continuous plenum — the results deduced from the kinetic theory — impulsion or the phenomena of the radiometer — arrangement of the paper — statement of the laws established by experiment . .... . ... 257 — 264

Section II. — Experiments on thermal trmispiration

Description of the apparatus and tests appUed — drying the gas — differences of temperature — the porous plates — the first results with air — hydrogen — maximum difference of pressure — carbonic acid — stucco plates — corresponding pressures with stucco and meerschaum — logarithmic homologues — a method of reducing the experimental results — comparison of the results with the laws stated in Art. 9 . . . 264 — 290

Section III. — E.vperiments on traTispiration under pressure

Graham's results — necessity for further experiments — the apparatus — equal volumes — measurement of the time — purity of the gases — experimental results — comparison of logarithmic homologues — relative coarseness of the meerschaum and stucco plates — corresponding results at densities corresponding to the fineness of the plates — Graham's results reconciled — verification of Law 1, Art. 9 . . . 290 — 299

Section VI. — Notation and p'eliniinary steps

Explanation of the symbols tr^ (Q), A, B, C, D, E, F, O, H—the rates at which mass, momentum, and energy are carried acros.s a plane by any one of the groups A, B, C, &c., in a imiform gas — Maxwell's law of distribution of velocities in a uniform gas — Restriction to gases of uniform textiu-e, such as air or hydrogen — Table XX. — Values of o- (Q) 312 — 318

Section VII. — Foundations of the theory. The inean range

The condition of the gas varying from point to point — line of thought — sketch of the method by which the fundamental theorems are deduced — the mean component velocities of the moleoides which pass through an element — limitations and definitions — condition of the gas — resultant uniform gas — ineqvialities — fundamental assumptions — fundamental theorems (I. and II.) — corollaries — the mean range s — the mean component values of s — general expressions for o- (<J>) when the gas is continuous — o-(§) in the neighbourhood of a sohd surface . . . 319 — 340

Section VIII. — Equations of motion. Equations of steady condition — steady density, momentum, and pressure

— conditions of no tangential stress in the gas or on a solid surface . 340 — 342

Section IX. — Amplication to transpiration and thermal transpiration through a tube

Equations of steady condition — transpiration under pressure when s is small compared with c, the distance across the tube — relation between s, fj., and other quantities — general case of transpiration and thermal transpiration —the value of Sj — Sj near a solid surface — the velocity of the gas and the friction at a solid surface — the equations of motion as affected by discontinuity — general form of Sj' — %' — general equation of transpiration .... 342 — 352

Section X. — Verification of the general equation

Statement of experimental residts — application of the general equation to the transpiration of a gas of uniform texture — application of the general equation to transpiration arising from varying molecular texture 352—362

Section XL — Application to apertures in thin plates and impulsion.

Equations of motion — condition of the gas — thermal transpiration through an aperture in a thin plate — thermal impulsion near a surface — between two smfaces — general equation of impulsion 362 — 371

Section XII. — Application to the fibre of silh and the radiometer

Corresponding results when the density is proportional to the smallness of the vane — other results — authoi^'s earlier conclusions confirmed in so far as they went — force depends on the divergence of the lines of flow as well as on the heat communicated, figs. 12-14 — figiu'es indicate the divergence of the lines of flow and the force in the radiometer — stability of the equilibrium — the motion — other points — action does not depend on the distance between the hot and cold plates . . 371 — 378

Section XIII. — Summary and Conclusion

General summary — dimensional properties of gas — conclusion . . 378 — 381