He was afterwards transferred to the geology department, and in December 1901 accompanied Professor F. T. Gregory on his expedition to Central Australia. In the preface to The Dead Heart of Australia Gregory paid a special tribute To my assistant Mr Grayson on whom much of the hard work of the expedition fell. In 1910 Grayson was associated with Daniel James Mahony in the preparation of a paper on The Geology of the Camperdown and Mount Elephant Districts (No. 9 in the Memoirs of the Geological Survey of Victoria), and in the same year, while working at the university under professor E. W. Skeats, who succeeded Gregory, Grayson made a highly efficient apparatus for preparing rock sections, a description of which will be found in the Proceedings of the Royal Society of Victoria for the year 1911.