Corrections

January, page S-9—In the 21st line of text in “What is the Cosmic X-Ray Background Telling Us About the Quasars Missing at High Red Shifts?,” “evaluation” should read “evolution.”

April, pages 35, 37—In “The art and physics of soaring” by Lloyd Hunter, there are several errors. The discussion of part b of figure 1 on page 35 distinguishes the various lines by structure. The figure, as printed, distinguishes them by color. To follow the argument, one must know that the “solid line” is green, the “dashed line” is orange and the “short dashed line” is blue. The same thing occurs in connection with figure 3 on page 37, where the “dashed curves” are now solid green lines. Also, on page 35, the slope of the polar curve is not the reciprocal of the glide ratio, as stated. Rather, the slope of a line from the origin to any point of the polar curve is the reciprocal of the L/D of the sailplane when flying at the speed representing that point.

April, pages 40, 41—Several errors appear here in the equations. In the second equation on page 40 Q should be V. In the fourth equation $\mathrm{D-h/S}$ should be $\mathrm{(D-h)/S}$. In the fifth equation $\mathrm{D-h/c}$ should be $\mathrm{(D-h)/c}$. In the first equation on page 41, ${\mathrm{c\; +\; S}}_0\mathrm{/B}$ should be ${\mathrm{(c\; +\; S}}_0\mathrm{)/B}$, and in the second equation C should be c.