Alberto, Yes it is, is the short answer. In fact you will need two shaped gnomons - one for the spring and one for the autumn. For each gnomon to stay in one piece, it has to have some notional diameter to which the EoT is added or subtracted. In the morning one side of the gnomon will cast the shadow, whilst in the afternoon it will be the other side. This means that at noon there are two parallel lines, separated by the notional diameter of the gnomon. This allows for the change of which edge of the shadow you read. I don't know if I've explained this as clearly as I should, but if you need more information, drop me an email.
My father makes an equatorial dial with just such gnomons and I have attached a photo of one - I hope it's not too big a file (apologies if it is). Regards, David Robert Higgon London Attachment converted: MAC Hard Disk:CONNOISB.JPG (JPEG/JVWR) (00009762)
