Accordingly, in 1851 he went to Vienna for the purpose of doing post-graduate work in the natural sciences at the university there. During the two years he spent at this institution he attracted attention by his serious application to study, but apparently without having given any special evidence of the talent for original observation that was in him. In 1853 he returned to the monastery in Altbrünn, and at the beginning of the school year became a teacher at the Realschule in Brünn. He remained in Brünn for the rest of his life, dying at the comparatively early age of sixty-two, in 1884. During the last sixteen years of his life he held the position of abbot of the monastery, the duties of which prevented him from applying himself as he probably would have desired, to the further investigation of scientific questions. The experiments on which his great discoveries were founded were carried out in the garden of the monastery during the sixteen years from 1853 to 1868. How serious was his scientific devotion may be gathered from the fact that in {203} establishing the law which now bears his name, and which was founded on observations on peas, some 10,000 plants were carefully examined, their various peculiarities noted, their ancestry carefully traced, the seeds kept in definite order and entirely separate, so as to be used for the study of certain qualities in their descendants, and the whole scheme of experimentation planned with such detail that for the first time in the history of studies in heredity, no extraneous and inexplicable data were allowed to enter the problem. Besides his work on plants, Mendel occupied himself with other observations of a scientific character on two subjects which were at that time attracting considerable attention. These were the state and condition of the ground-water--a subject which was thought to stand at the basis of hygienic principles at the time and which had occupied the attention of the distinguished Professor Pettenkofer and the Munich School of Hygiene for many years--and weather observations. At that time Pettenkofer, the most widely known of sanitary scientists, thought that he was able to show that the curve of frequency of typhoid fever in the different seasons of the year depended upon the closeness with which the ground-water came to the surface. Authorities in hygiene generally do not now accept this supposed law, for other factors have been found which are so much more important that, if the ground-water has any influence, it can be neglected. Mendel's observations in the matter {204} were, however, in line with the scientific ideas of the time and undoubtedly must be considered of value.