On researching the Black Plague I have a few times run into the name of "Heckler" who supposedly is the source for the information that 25% of the population of Europe was killed by the plague. For example, one mention is as follows:
The black death, which visited London in the fourteenth century, is now merely of historic interest; yet it reminds us of a period when there were no hospitals, no buildings in which the plague-stricken could be separated from the healthy, no scientific physicians, no trained nurses; in short, no effective means whatever for combating a scourge which terrified a people for six years, and according to the chronicler Heckler, paralyzed morals, religion and education, and resulted in a collapse of civilization which continued to be felt for generations. (Journal of the American Medical Association, Volume 59, Issue 19, p. 1672.)
Unfortunately, none of the citations give any further information about this person and I can find no record in English or German bibliographies of a chronologist or medical statistician named Heckler. Does anybody know who this guy was?