1414
THEORY AND PRACTICE OF ENGINEERING.
Book LL
To Nicholas Zabaglia,who was born at Rome in 1674, we are indebtedfor designs of some of thebest scaffolds that havebeen erected. This ce-lebrated mechanic, firstemployed at the Vatican as a carpenter, afterwardsbecame the chief directorof the works at St.
Peter’s: Jean Bottari,the librarian of the Va-tican , collected severalof his designs for scaffold-ing, which are publishedunder the title of “ CasteUie Ponti di A7c. Zabaglia , con alcuneingegnose pratiche, e con la Descri -zione del Trasporto del ObleliscoVaticano e di altri del Dorn Fontana ,1743.” In one of the platesthe scaffold-builder is representedin his workshop examining theforce of a pulley, and of the fifty-four, thirty-six are designs ofvarious machines to assist in con-struction ; they are exceedingly in-teresting, and should be in thepossession of every civil engineer.Caylus considered the talents ofZabaglia as of a very superiorkind, and Passeroni commemoratedthem in his poem called “ II Ci-cerone." In the construction ofthe scaffolding at St. Peter’s, hemade use of the holes left in thevaulting, for the purpose of sus-pending, by means of iron rods,platforms, upon which the work-men stand to clean or re-colourthe soffites.
Fig. 2361.
Fig. 2362.
Turning Scaffohls may be attachedto a revolving pole with two arms,acting like the radii of a circle, whichmay be Taised or lowered at pleasure:these arms carry a platform attachedby iron hooks, on which stand theworkmen; by means of ropes and pulleys
Fig. 2363.
Fig. 2364.