John Anthony, physician and naturalist, was born at Riga on the 26th of April 1745, received the rudiments of his education in that town, and in 1763 was admitted into the medical college of Berlin. He completed his studies at Frankfort-upon-the-Oder, and in 1767 took the degree of doctor of physic in that university. On account of his knowledge of foreign languages, and the progress he had made in natural history, he was considered as a fit person to engage in the expeditions which were planned by the imperial academy of St Petersburg. Being invited to that capital, he in 1768 proceeded thither, and was created adjunct of the academy, and in 1770 member of that society, and professor of natural history. In June 1768 he set out upon his travels, and was absent seven years. From Moscow, where he continued till March 1769, he passed to Voronetz, Tzartzin, Astrakan, and Kislar, a fortress upon the western shore of the Caspian, and close to the confines of Persia. In 1770 he examined the districts watered by the rivers Terek, Sunsha, and Alksai, in the eastern extremity of Caucasus; and in the course of the ensuing year penetrated into Ossetia, in the highest part of the same mountain, where he collected vocabularies of the languages spoken in those regions, made inquiries into the history of the people, and discovered amongst them some traces of Christianity. Having visited Cabarda and the northern chain of the Caucasus, he proceeded to Georgia, and was admitted to an audience of Prince Heraclius, who had encamped about ten miles from Tiflis. Having passed the winter in examining the country adjacent to that place, he in spring followed the prince to the province of Kaketia, and explored the southern districts inhabited by the Turcoman Tartars in the company of a Georgian noble, whom he had cared of a dangerous disorder. In July he passed into Imeritia, a country which lies between the Caspian and the Black Sea, and is bounded on the east by Georgia, on the north by Ossetia, on the west by Mingrelia, and on the north by the Turkish dominions. He penetrated into the middle chain of the Caucasus, visited the confines of Mingrelia, Middle Georgia, and Eastern and Lower Imeritia; and, after escaping many imminent dangers from the banditti of those parts, fortunately returned on the 18th of November to Kislar, where he passed the winter, collecting various information concerning the neighbouring Tartar tribes of the Caucasus, and particularly the Lesgees. In the following summer he proceeded to Cabarda Major; continued his course to Mount Beshtou, the highest point of the first ridge of the Caucasus; inspected the mines of Madshur, and then directed his course to Tchercisk up the Don. From this place he made expeditions to Azof and Taganrog, then along the new limits to the Dnieper, and terminated this year's route at Kremenshtuk, in the government of New Russia. In the ensuing spring he was proceeding to Crim Tartary; but having received an order of recall, he returned through the Ukraine to Moscow and St Petersburg, where he arrived in the month of March 1775. Upon his return he was employed in arranging his papers; but before he had time to prepare them for the press, he was seized with a malignant fever, which carried him to the grave in March 1781.

Guldentstaedt is the author of, 1. Several Memoirs in Latin, relative to natural history and botany, and containing descriptions of unknown animals and vegetables which he had observed in the course of his travels; 2. Different Memoirs on the history, geography, statistics, and commerce of various parts of Russia; 3. Travels in Russia and in the Mountains of Caucasus, St Petersburg, 1787, 1791, in two vols. 4to, with maps, plans, and figures; 4. Memoir on the products of Russia, calculated to maintain the balance of Commerce always favourable, 1777, in 4to. The labours of Guldentstaedt, as a scientific traveller, have proved very useful to the learned who have written on the Caucasus; and all of them mention his name with commendation. Pallas was the editor of his narrative; but he did not arrange the materials in very regular order, and, besides, intrusted the correction of the press to incompetent hands, the consequence of which has been numerous errors in the orthography of proper names, and even in that of the German words, whilst entire phrases have been omitted. The second volume, which Guldentstaedt had himself prepared for the press, has been printed in a manner less faulty. But the first is the most interesting, because it contains the description of the Caucasus; a region which may almost be regarded as the birthplace and nursery of modern nations.

GULE of August, the day of St Peter ad vincula, which is celebrated on the first of August. It is called the gule of August, from the Latin gula, a throat, because one Quirinus, a tribune, having a daughter with a disease in her throat, went to Pope Alexander, the sixth in succession from St Peter, and desired of him to see the chains with which St Peter was bound under Nero. His request was granted; and the young woman, having kissed the fetters, was cured of her disease; whereupon the pope instituted this feast in honour of St Peter, and the day was on this occasion called indifferently either the day of St Peter ad vincula, from the fetters which wrought the miracle; or the gule of August, from that part of the virgin on which the miracle was wrought.