Daniel was born in Westmoreland Co., PA, September 10, 1817, and passed away at the age of 70 in Muscatine, IA. Daniel was legally blind, lived with his relatives throughout his lifetime and worked as a manual laborer. For a large part of his life he resided with relatives in Morrow Co., OH before his final days in Iowa. Daniel was buried with brothers Isaac R. and Robert, and their mother Lydia in Oakdale Cemetery, Wilton Jct., IA. At the time of my first visit to Oakdale Cemetery in 1990, a wooden board with no inscription marked Daniel's grave (see photo above). On a later visit several years later, the three boards representing headstones had been removed. I believe that the three boards had been placed there and were maintained by an older living relative residing in Wilton who has since passed away.

Hyperthymestic Syndrome
Daniel had a rare ability/condition which enabled him to effortlessly remember every single day in his life from the age of nine up until his death. Given any specific calendar date, Daniel in seconds, would mentally respond with the following information: 1) the day of the week; 2) the weather; 3) what he did during the course of the day; 4) what he ate for breakfast, lunch and dinner; and 5) describe events that occurred, locally, regionally and nationally. In a recent and similar case as Daniel's, noted neurobiologist Dr. James McGaugh of the University of California-Irvine (UCI), one of the world's leading experts on human memory, reports on a woman named Jill Price of California, with the astonishing ability to clearly remember events that happened to her decades ago. Dr. McGaugh labels this one-of-a-kind ability as Hyperthymestic Syndrome ["Woman's Long-Term Memory Astonishes Scientists", NPR, April 20, 2006]. Dr. McGaugh and his team of researchers are also studying two other identical cases; Rick Baron, a game show contestant of Ohio and Brad Williams, a radio DJ of LaCross Wisconsin. Daniel's case appears to be indistinguishable from these individuals being studied at the UCI. Daniel, however, was unique in another respect--he had an additional mental ability - mathematical computation.

Mathematical Computation
Daniel could mentally compute difficult mathematical problems in seconds, and extremely difficult computations in minutes. Daniel was tested several times by panels of university mathematicians and theologians in which he was given a battery of mathematical questions. On one such examination in July 1870 in Salem, OH, Daniel was asked an extremely difficult problem - to take 89 to the sixth power [89 x 89 x 89 x 89 x 89 x 89], which he mentally computed in ten minutes, giving the correct answer of 496,981,290,961! On another examination he was asked to provide the cube roots of 4,741,632--[ ( __ x __ x __ ) = 4,741,632] for which he answered correctly in three minutes-(168); and 389,017--[ ( __ x __ x __ ) = 389,017] for which he answered correctly in fifteen seconds-(73).

Public Demonstrations
On occasion, Daniel and his relatives would host special sessions for the general public to see him, and would charge admission for the purpose of asking him mathematical, calendar dates, weather related and local, regional and national events questions. Daniel was always correct in his responses, and would provide a response in a matter of seconds to the amazement of audiences. One such exhibition occurred on the evening of March 29, 1871 at the Opera House in Columbus, OH. State Commissioner of Common Schools, W. D. Henkle, began this particular public examination of Daniel's powers. The audience was allowed to propose calendar dates. This was followed by questions in numbers, proposed by E. E. White, editor of the Ohio Educational Monthly and National Teacher. Mr. White's questions were followed by an examination in the New Testament by Rev. G. W. Phillips, of Columbus. Daniel sustained himself triumphantly during an hour's questioning. The impression left in the minds of the Legislators, State officers, Judges, and others present, was that, "Mr. McCartney’s memory is wonderful". Chief Justice Josiah Scott remarked to Judge White and W. D. Henkle, on the way from the Opera House, that, "If that man had appeared before him as a witness, claiming to give the time of events with such accuracy, he would have felt like sending him to jail as an impostor, but now it would take a good many witnesses as to dates, to counteract his testimony."

Many articles about Daniel's unbelievable memory and mathematical aptitude can be found in encyclopedias, books, newspapers, scholarly journals and the Internet, and/or references to him (see Daniel's Bibliography).