Prepare for cooking the onions, carrots and turnip cut in slices, and cook slowly in a pint of boiling water until they fall to pieces, cook with them until tender a celeriac root, remove from the other vegetables and put one side. Melt the butter in a saucepan, and stir in the flour, curry powder, mix well together and then add the milk. Strain the vegetables through a fine sieve, but do not press them, and add the stock therefrom to the milk, etc., in the saucepan, and salt to taste. Beat the cream with the egg yolks until light, remove the soup from the fire, mix a little of it with the eggs and cream, turn it back into the saucepan, stir well together and pour at once into the tureen in which you have already placed the celeriac cut in slices. If liked, two tablespoonfuls of Madeira may be added just before the soup is turned into the tureen. Serve with croutons.