What does Sir refer to?

Does it refer to editors of Nature? Or general readers of the magazine Nature?

Context:

Leading scientists still reject God
Nature, Vol. 394, No. 6691, p. 313 (1998) ?Macmillan Publishers Ltd.

Sir — The question of religious belief among US scientists has been debated since early in the century. Our latest survey finds that, among the top natural scientists, disbelief is greater than ever — almost total.

Research on this topic began with the eminent US psychologist James H. Leuba and his landmark survey of 1914. He found that 58% of 1,000 randomly selected US scientists expressed disbelief or doubt in the existence of God, and that this figure rose to near 70% among the 400 "greater" scientists within his sample [1]. Leuba repeated his survey in somewhat different form 20 years later, and found that these percentages had increased to 67 and 85, respectively [2].

In 1996, we repeated Leuba's 1914 survey and reported our results in Nature [3]. We found little change from 1914 for American scientists generally, with 60.7% expressing disbelief or doubt. This year, we closely imitated the second phase of Leuba's 1914 survey to gauge belief among "greater" scientists, and find the rate of belief lower than ever — a mere 7% of respondents.

Leuba attributed the higher level of disbelief and doubt among "greater" scientists to their "superior knowledge, understanding, and experience" [3]. Similarly, Oxford University scientist Peter Atkins commented on our 1996 survey, "You clearly can be a scientist and have religious beliefs. But I don't think you can be a real scientist in the deepest sense of the word because they are such alien categories of knowledge." [4] Such comments led us to repeat the second phase of Leuba's study for an up-to-date comparison of the religious beliefs of "greater" and "lesser" scientists.

Our chosen group of "greater" scientists were members of the National Academy of Sciences (NAS). Our survey found near universal rejection of the transcendent by NAS natural scientists. Disbelief in God and immortality among NAS biological scientists was 65.2% and 69.0%, respectively, and among NAS physical scientists it was 79.0% and 76.3%. Most of the rest were agnostics on both issues, with few believers. We found the highest percentage of belief among NAS mathematicians (14.3% in God, 15.0% in immortality). Biological scientists had the lowest rate of belief (5.5% in God, 7.1% in immortality), with physicists and astronomers slightly higher (7.5% in God, 7.5% in immortality). Overall comparison figures for the 1914, 1933 and 1998 surveys appear in Table 1.

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http://www.stephenjaygould.org/ctrl/news/file002.html