In the last issue of the CSA Newsletter I wrote about our adaptation of Alum-A-Pole scaffolding for use on the Propylaea (see Harrison Eiteljorg, II, "An Apparatus to Aid in Surveying High Walls," XX,3; Winter, 2008; http://www.csanet.org/newsletter/winter08/nlw0801.html). The proof-of-concept trip to Athens was successful, but there remained some work to do if the raising of a taller version of the scaffolding -- required for our survey work on the Propylaea -- were to be accomplished by a small crew of people without unusual physical strength.
I promised a plan and a report on that plan by a date that has receded into the mist. In fact, a plan has been developed and tested, but the initial tests were done with a version of a new system that still needs refinement.
Two earlier systems were tried, each based upon an idea I had already begun to develop at the time of the last Newsletter. Both versions of the general idea were successful in the sense that they accomplished the task at hand, raising a 36-feet-long post, but both showed that even a workable plan should be more practical. The second of the two plans was acceptable, but even it fell short of real simplicity. Both involved ladders -- two for the first and less practical plan and one for the second and more workable plan -- positioned against the wall toward which the post was to be hoisted. In both plans the ladder or ladders provided a high attachment point for a pulley via which the post could be raised. Putting the pulley relatively far off the ground allowed us to pull the post from a point farther from its bottom and with only the mechanical advantage supplied by three loops to/from pulleys (a 3:1 mechanical advantage). Since neither experiment resulted in the kind of success that is both technically successful and truly practical, I will spare you a fuller explanation here, but it seems necessary to point out that, once again, the work had its moments of levity and minor injuries involving little or no blood.
After the second experiment, John McMurtrie, a CSA board member, recommended a different approach that lead in a different direction -- and to a successful experiment that will provide the base for a more refined system. I will write again about the final system when it has been fully designed and tested, but I can say now that it provides both technical success and practical utility. This system makes use of a winch for greater mechanical advantage (35:1). That increased mechanical advantage permits us to raise the post with a rope or cable attached to the post at a point relatively close to its bottom; attaching there raises substantially the effort required to raise the post, making the winch critical. Since the attachment point on the post is lower in this system, there is no need for a ladder or any other device to make it possible to pull the post from a point higher off the ground. Anyone wanting to know more without waiting for the next issue of the Newsletter should contact me for details. [The wait for a fuller explanation in the Newsletter will be longer than anticipated; the next article will not appear until the January, 2009, issue, which will be posted after work in Athens planned for October, 2008, has been completed. Note added September 16, 2008.] In the meantime, I can say that it is certainly possible to position people next to a wall and more than forty feet in the air without the use of expensive or exotic equipment.
-- H. Eiteljorg, II