Dr. Augustus Le Plongeon, during the last quarter of the year 1875, made an extensive exploration of Chichen-Itza. The reports of his discoveries seem at first well-nigh fabulous, though their authenticity is so well attested as to leave no room for doubt. Mr. Stephen Salisbury, Jr., of Worcester, Massachusetts, has in several memoirs of intense interest and unusual scientific value, communicated the progress and results of Dr. Le Plongeon’s exploration in Yucatan to the American Antiquarian Society. Mr. Salisbury has also presented the explorer’s original memoirs, accompanied by photographs made at Chichen-Itza and on the Islands of Cozumel and Mugeres. These valuable documents have reached the public in Mr. Salisbury’s publications entitled, (1.) _The Mayas, the Sources of their History_ (Worcester, 1877, with heliotype reproductions of the photos); (2.) _Maya Archæology_ (Worcester, 1879, with heliotype reproductions of photos and drawings).[569] In these pages we are impressed with the fact that the darkness which has so long enveloped the antiquity of Yucatan is soon to be displaced by the noon-day of scientific investigation. Still we cannot refrain from expressing the regret that Dr. Le Plongeon’s enthusiasm is so apparent in his reports. A judicial frame of mind, as well as the calmness which accompanies it, are requisites both for scientific work and the inspiration of confidence in the reader. Notwithstanding this, our views have been most happily expressed by the committee of the American Antiquarian Society, to whom was entrusted the publication of Dr. Le Plongeon’s memoirs. Their statement is as follows: “The successes of Du Chaillu, Schliemann, and of Stanley, are remarkable instances of triumphant results in cases where enthusiasm had been supposed to lack the guidance of wisdom. If earnest men are willing to take the risks of personal research in hazardous regions, or exercise their ingenuity and their scholarship in attempting to solve historical or archæological problems, we may accept thankfully the information they give, without first demanding in all cases unquestionable evidence or absolute demonstration.”