Concerning the article on the restoration of Rembrandt's "The Anatomy Lesson of Dr. Nicolas Tulp," (Chemistry diagnoses a painting's ills," SN: 3/13/99, p. 166), it bears repeating that the lesson itself must have been unique, for the common origin of the flexor muscles of the forearm is the medial epicondyle, whereas the painting would have you believe it is the lateral epicondyle. This error is well known and would not allow an examiner to pass a student who offered Rembrandt as an expert in the matter.

Nick De Morgan
Portland, Ore.

The article "1998: Warmest year of past millenium" (SN: 3/20/99, p. 191) is interesting, but the graph presents a big question. Over the past 100 years, a significant amount of warming occurs from the turn of the century to around 1935. Temperatures then level off until about 1980. Another large upspike then ensues until the present. This behavior does not correlate well with the growth of fossil-fuel combustion. Is there another effect of human activity?

Dean Musgrave
Dearborn, Mich.

Your story "Moon's tiny core hints at earthly origin" (SN: 3/27/99, p. 198) says the idea that the moon is an offspring of Earth has been around ever since the first samples of lunar rocks came back from the moon. Actually, the idea is older than that. Rachel Carson (of Silent Spring fame) wrote in her charming book The Sea Around Us (1950), "We immediately wonder what became of the Pacific's granite covering and the most convenient assumption is that it was torn away when the moon was formed. There is supporting evidence. The mean density of the moon is much less than that of the Earth (3.3 compared with 5.5), suggesting that the moon took away none of the Earth's heavy iron core, but that it is composed only of the granite and some of the basalt of the outer layers."

Paul Lyrene
Gainesville, Fla.

The idea that the moon is an offspring of Earth has been around much longer than the article states. For example, it was presented by George Gamow in his Biography of the Earth (1941), although he suggested a different mechanism for the moon's birth. He gave credit to Sir George Darwin (1845-1912).

Peter Yff
Muncie, Ind.

The article "New support for echinacea's benefits" (SN: 3/27/99, p. 207) failed to address a large body of clinical research on various species of echinacea. Though many of these studies have had flaws, they overwhelmingly support the view that echinacea can shorten the duration and severity of the common cold. On the other hand, recent double-blind studies have not supported the historical use of echinacea for prevention of the common cold. The article's claim, "Less easy to find have been scientific studies that back up echinacea's reputed infection-fighting powers," is simply false.

Eric Yarnell
Sedona, Ariz.