Worth his salt

Aisling Irwin (THES, September ) dates "the birth of animal rights" with the publication of Paul Singer's Animal Liberation in 1975 and the notion of "rights" as derived from the United States. Henry Salt's essay on animal rights was published in the journal, Ethics in 1899 and his book Animal Rights in 1892. Singer knows this. He wrote the preface for the 1980 edition of the latter.

D. Weinbren Faculty of humanities School of history and politics Middlesex University