Thanks, folks. It took about 10 minutes longer to bake this cake than the recipe stated, so it may be that when I opened the oven door to, hopefully, take it out, that's what did the damage. (Oh, what a gift 'twould be to gi'e us, to have an oven with a window!!) My oven keeps perfect temperature, so there is obviously something wrong with the recipe. Fanny is not always right--I have a few of her recipes that I've crossed out of the book because they fail miserably. I'll try this one again and just leave it in the oven, unchecked, for an extra 10 minutes.
Thanks again.