That event was the exhibition of the 'unfinished' oils by Turner at the Tate Gallery.
Plate XLIV. Spietz on the Lake of Thun, Looking Towards the Bernese Oberland. Water colour (1842) In the collection of W. G. Rawlinson, Esq. (Size, 14 x 9 5/8)
[CHAPTER LVII]
1906: EXHIBITION OF THE 'UNFINISHED' TURNERS AT THE TATE GALLERY
The event was heralded by the following paragraph communicated to the Press by the Director and Trustees of the National Gallery:— 'Unexhibited Oil Paintings; Turner's Bequest. The Turner Collection of paintings, placed in the custody of the National Gallery Trustees, on September 25th, 1856, contained, besides the pictures since hung in Public Exhibition Rooms, or in the Official Rooms at Trafalgar Square, or lent under the Loan Act of 1883 to Provincial Museums, a certain number of paintings which, on account of their unfinished or wrecked condition, it has never been thought possible to exhibit.
'A more careful examination has lately led the Trustees to believe that some, at least, of these paintings may now be framed and take their place in the general collection. A selection has been made for this purpose, and of the paintings selected, many have been relined, and all are in course of being surface cleaned and varnished.'