‘acute steel canopies’, the reading of the Ruskin Library Transcript T7B, seems implausible. ‘acute shell canopies’ seems preferable. There is no exact precedent in Ruskin, but there are other uses of ‘shell canopy’: Works, 11.306 (and compare Works, 11.106 and Works, 11.290) and of canopies which are ‘never very acute’ - Works, 12.199.
[Version 0.05: May 2008]