Ellicott City, Md., May 18, 1899.
To the Editor:
—I note in the Journal of April 29, under "Public Health," that a prize has been awarded Dr. Caslaing "by the French Academy of Science, for his suggestion that two upper panes in each window be replaced with double panes a short distance apart, the outer pane leaving a narrow opening at the bottom, as it does not reach quite to the sash below, and the inner pane leaving a similar opening at the top, as it does not reach quite up to the top of the sash."This seems a curious thing, when we read in Parkes' "Hygiene" (Edition 1883, Wood's Library, p. 174, Vol. i), in speaking of natural ventilation and its practical application: "Various plans have been proposed by different persons. The panes of glass may be made double, spaces being left at the bottom of the outside