AN EXPLORATION OF MACKENZIE RIVER, Great Slave lake and river, and Lake Athabaska. Mr. Ogilvie ascended this great waterway and prepared a report which is still much consulted. In 1891 Mr. Ogilvie, under the direction of the Surveyor-General, again made an exploratory survey in the same region. Mr. Ogilvie’s instructions were to make a thorough exploration of the region drained by Peace river and its tributaries, between the boundary of British Columbia and Rocky mountains and to collect any information that might be of value relating to that region. As it was desirable that he should, if practicable, connect the end of his micrometer survey of Mackenzie river made in 1888 with that made on Great Slave river in the same year, which he was then unable to accomplish on account of high water, Mr. Ogilvie took with him the necessary instruments, but he found it impossible to complete this work. This time, he descended the great northwestern waterway from Athabaska to Fort Simpson, and, ascending the Liard and “East Branch” or Nelson river, as it has since been officially called, reached Port Nelson on September 15, ascending Nelson and Sikanni Chief rivers and portaging through the woods to St. John on Peace river. Another interesting report was the result of this really hazardous trip. In 1886, Mr. A. P. Low of the Geological Survey, accompanied by Mr. J. M. Macoun, crossed Lake Winnipeg from Red river to Berens river and ascended the latter to a portage to the head waters of Severn river, making an exploration of the country from Lake Winnipeg to Hudson bay. In 1887, Mr. R. G. McConnell, B.A., of the Geological Survey, descended to Mackenzie river from the Yukon via Liard river, and during that year and the following one explored a considerable part of Mackenzie basin including Slave river, Salt river, Hay river, part of the western end of Great Slave lake, etc. The result was embodied in a most interesting official report (Part D. Annual Report, Vol. IV., 1888-89, Geological Survey of Canada.) The country between Peace and Athabaska rivers north of Lesser Slave lake, comprising an area of about forty-four thousand square miles, remained entirely unknown until Mr. McConnell’s exploration was undertaken. In the years 1888, 1889, 1890 and 1891, Mr. McConnell effected a most important exploration of the unexplored country between Peace river and Athabaska river and in the basin of the Athabaska. He investigated as thoroughly as he could the phenomena of the so-called tar-sand deposits and the OIL SPRINGS OF ATHABASKA REGION, about which the few hunters, traders and travellers who had hitherto penetrated so far had brought back such astonishing tales. His report, printed in the annual report of the Geological Survey of Canada for 1890-91 (New Series, Vol. V, Part I), excited much interest at the time throughout the scientific world, and is still regarded as the standard authority on the subject.