Good scientific essayists?

Stephen Jay Gould produced fantastic essays on a weekly basis - around 10pgs in length they were always witty, informative, and generally suitable for they semi-informed lay person. But the essay is a seldom used scientific tool and since his death I haven't found anyone to replace him for the physical, natural, or social sciences. I know Richard Dawkins has occasionally dabbled, but does anyone have any tips for any really good scientific essayists?