This section is from the book "Elements Of The Theory And Practice Of Cookery", by Mary E. Williams. Also available from Amazon: Elements Of The Theory And Practice Of Cookery; A Textbook Of Domestic Science For Use In Schools.
3. The proper degree of heat for baking must be learned by experience. In general, doughs require a hotter oven than batters do. Too great heat causes bubbles of air or gas to burst and run together, a condition which is to be avoided when a fine-grained bread is desired. Popovers, when baked, should be hollow shells, and so require a very hot oven at first.
4. Set the pan at first on the bottom of the oven; after the bread has risen it may be placed on the rack to brown the top.
5. Open and close the oven door gently - "as if there were a baby inside" - and if it is necessary to move the pan while the bread is rising, do it carefully. A draft of cold air will cause the bubbles to collapse; a sudden jar will break them. In either case the bread will fall.