Bridge of SighsAmazon. com Robin Trower left Procol Harum to pursue his own musical vision and, while Spinal Tap has made the efforts of those who pursued such "heaviness" seem positively ludicrous, one listen to side one of Bridge of Sighs should prove once and for all that such pursuits are not always in vain. Trower leads a power trio of unrestrained heaviness, anchored by his sublimely bloated lead guitar and bassist James Dewar's throaty vocals. The wind sounds