<div class="htmlview paragraph"><b>THIS paper presents an unusually comprehensive review of automatic transmissions, past and present - domestic and foreign. Operating principles, limitations, advantages, and disadvantages of each of many types are explained with the aid of cross-sections and diagrammatic sketches.</b></div> <div class="htmlview paragraph"><b>The author points out that automatic transmissions are not new, the first one being developed in 1900, and the first car equipped with one was placed on the market in 1904.</b></div> <div class="htmlview paragraph"><b>This first transmission, invented by George S. Strong, employs a roller-ratchet drive and is of the infinitely-variable type. Also described under this heading are the de Lavaud automatic transmission and the R.v.R. automatic torque converter. Hydraulic types of infinitely-variable automatic transmissions discussed include the Waterbury and the Lysholm-Smith hydraulic torque converters. Inertia-type automatic transmissions take up the Spontan, the Constantinesco, and the Hobbs. In the self-shifting category are grouped the Sturtevant, Yellow Coach, Macallen, Prince and Tyler.</b></div> <div class="htmlview paragraph"><b>In the review of differential transmissions that concludes the paper are included electric and hydrostatic, the Entz electric transmission, the Electrogear unit, and the Bendix Turbo Flywheel Gear.</b></div>