THIS exhibition is mounted in the new Print Room, on mezzanine floor, and a very sympathetic - and elegant - setting it makes, too. The works seemingly all come from the National Gallery's gown collection, ranging over three centuries.

Perhaps the golden age of pastel was in the 18th century, particularly in the hands of French virtuosi, who found, that they could produce excellent, informal portraits in this medium without the tedium and/or complication of long sittings. There is a fine portrait of a nobleman by Maurice Quentin de la Tour and various pictures by another suave international virtuoso, Rosalba Carriera. Her series Spring, Summer, Autumn, Winter is all of young women; even Winter is a handsome, blooming blonde, not a wrinkled hag, as you might expect (no allegory intended here, it seems).

Hugh Douglas Hamilton is very prominent, depicting with style, and panache the gentry, soldiers and politicians of 18th century Ireland. He is, on the whole, much freer and more more himself in this medium than in oils. Robert Healy's pictures are really in, chalk but handled, as the notice on the walls says, in the style of pastel, so let us not be purist. There is a notable portrait of the Earl of Chesterfield (yes, he of the Letters to his Son) and some impressive works by Nathaniel Hone the Elder.

In the 19th century, two small sunset studies by Mulready are particularly noticeable. Millet's large Making Hay During a Storm - originally a Chester Beatty bequest - is a powerful, moody work, and the two fine Degas pastels, one of female dancers and the other of two male harlequins, were the gift of that much underrated man, Edward Martyn. What a shame, by the way, that today Martyn is almost solely remembered as the clownish straight man in George Moore's Hail and Farewell!

Rather a surprise is an almost romantic portrait by a Scandinavian artist, Anne Nordgren, of the young Countess Markievicz - or rather Constance Gore Booth, as she was then. Sean O'Sullivan's depiction of Sinead Bean de Valera is one of his occasional masterpieces, but the two Kernoff portraits - including one of Brendan Behan are coarse, and in the case of Behan I suspect that it was not done from life.

This is not a huge exhibition in terms of numbers, but it is rewarding all through and is well mounted. Glass cases in the middle of the rooms include, as an extra bonus, such items as three small Maillol bronzes.