A RAINY or cloudy day is the best time to drop by the National Gallery of Art's new exhibition of old master drawings from the National Gallery of Scotland.

Eyes dazzled by the summer sun will strain in vain to see the subtleties of these 86 drawings, which span the 14th through 18th centuries and include works of Bruegel, Cuyp, van Dyck, Fragonard, Piranesi, Raphael, Rembrandt, Rubens and Tintoretto.

It's an embarrassment of riches for our national gallery, which owns one of the world's largest and finest collections of old master drawings, and an embarrassment of another sort for those visitors not blessed with perfect sight. Conservation requires low-level lighting, and many of the drawings are so faded or yellowed that close inspection is required.

The exercise is fatiguing, but relief is at hand in the form of yet another excellent exhibition catalogue. One of the happy accidents of modern printing is that reproductions of old drawings often show up better than the originals, which is the case with this $30 bargain. Adding to the enjoyment of the drawings is the pithy commentary by the keeper of prints and drawings for the Scottish national gallery. Hugh Macandrew is a scholar who spends words as though he were being charged for each one.