At 09:22 6/21/97, you wrote: >At 15.19 21/06/97 +0300, you wrote: >>I am interested in the above mentioned types of sundial. >>1.Where was the gnomon placed un relation to the hour marked stone? >>2.Was there any indication as to the lattitude in that type of sundial. >>3. What is the difference between the hemispherical and the conical type? >>4. What kind of scientific knowledge did a maker have to possess in order >>to make such a dial? >>5. What kind of knowledge did the user have to possess? >> >> >-------------------------------------- > >Ronit, > > easy to respond to your questions. > >1. The gnomon was orizontal placed in the origin of the hour lines, at the >top of the curve (not easy to esplane without a drawing, indeed), not the >same in the hemisphaerium that it was an emispherical vase opened to the >zenit. In this last case the gnomon was standing right up pointing to the >zenit, but some medieval drawing and fisical example like that in the >Science Museum of Florence have the gnomon parallel to the eart axe. The >vertical inclined hemisphere use a hole in its top as gnomon. > >2) No, the only way to measure the latitude for what the dial was made, is >to measure the angle of the inclination of the dial. > >3) It depend on the meaning of the words, for me hemispherical means >hemispherical, that is a half of a sphere. In this case we have three tipe >of hemispherical roman dials: orizontal (I wrote before), vertical and >vertical inclined (I wrote before). Probably you mean the hemicyclium that, >following the meaning of the word it was a sundial done inside a, more or >less, a quarter of sphere. The hour lines are arcs of circle. On the other >hand the conical sundial is very similar to the hemiciclic one but the >section is conical and the lines are right. > >4) My experience say that those sundials was made in a great number by >artisans with an average scientific knowledge. Many of the instruments are >not so precise as they want to be, but good enough for common people. >Anyway, almost the leader of the workers, must know the "analemma". > >5) Normal knowledge to read it, and to do it, it's very easy. > >Short anwers mine. If something is not clear let me know. >Anyway you can look at the book of Mrs. Gibbs, "Greek and Roman Sundials", >or at the great bibliography that you can easily find. If you need help, >please write me. > >Regards > >Mario Arnaldi > >============================ >MARIO ARNALDI >Viale Leonardo, 82 >48020 Lido Adriano RAVENNA >ITALY > >E-Mail - [EMAIL PROTECTED] >---------------------------- > >Thank you very much for the explanations. They were very helpful. Could you possibly send me drawings of the 4 types of dials you mentioned? (conical +3 hemicyclic). Can you tell me of other books, besides Gibbs, who give a good clear explanation about those sundials?
Ronit Maoz Tirat Shalom Ness Ziona 70400 Israel
