Monday, July 28, 2014

Water Rockets and Raven Chasers

Iron roof tile with spikes for the
roof of the Sanctuary Building.
One of our family's pastimes is launching homemade water rockets at the park, and over the past few years we have also been bringing the rockets to our shul's annual barbecue where they have become an unofficial part of the day's activities. About a week before the big day we were out in the front yard doing some test flights when one of the rockets hit an ill wind and was blown off course. This is not really a problem since they are so light that they roll, or bounce, off any roof they land on. Usually.

We, however, have the honor of living in the house right next door to our shul, a shul which not only has an annual barbecue but also a brand new building, most of which is covered by a large, flat roof. After losing one rocket to the shul we resumed with the backup, but somehow this, too, found its way onto the roof.

Although, in general, we say that מעלים בקודש ולא מורידים which, in this case, I suppose means that we put things up onto holy places but do not bring them down from there, I really needed to bring those rockets down! Fortunately for me, the shul president has the laid-back sense of humor you would normally associate with the shul candy man — probably because he is the shul candy man — and he got a real kick out of the whole situation. Arrangements were made, keys were transferred, and a couple days later I was up on the roof.

The omnivorous crow (Wikipedia).
While I was climbing among the HVAC scouring the roof for my empty soda bottles, I saw a medium-sized, black bird flying overhead. It was a Baltimore raven, or maybe a Baltimore crow (I can't tell the difference), and it was carrying some sort of dead thing in its talons. As it flew, a smaller bird whose territory it had invaded — or perhaps whose mate it had just snatched — was pestering it, and the black bird needed a place to deposit its lunch. It landed on the peak of the sloped roof covering the main sanctuary of the shul and left its kill there while it flew away under a barrage of swoops.

It might not seem all that unusual or interesting, but this observation is a rare nugget of Tractate Middos brought to life. The scenario I witnessed was a familiar one to the builders of the Second Temple who were well aware that the tallest building around would soon be littered with the carcasses of dead sheratzim left by birds of prey. To maintain the holiness of the Temple their solution was to cover the roof with 1-amah tall iron spikes called כלה עורב, raven chasers, that would prevent birds from landing there. I was just working on my computer model of the roof of the Sanctuary Building and had to think about how many spikes were needed. Spacing them so that the distance between one spike and the next is less than the size of a bird would certainly do the trick, but I do not think that it was necessary to use so many. A young man from Israel once told me that on his kibbutz they set up a grid of ropes over their pond to deter pelicans (or some kind of large water fowl) from landing on the pond and eating the fish. When the birds see that they do not have enough room for a safe landing, they stay away. A quick search showed me that the same concept is used for keeping out ducks and geese as well. Therefore, the iron spikes on the roof need only be spaced far enough apart to make the birds fearful of landing there, although I have no idea just how far apart this is, so I think a call for papers is in order. The experiment may be purely academic, however, for just as in the First Temple there were no spikes on the roof since G-d's Presence was so palpable that the birds were naturally kept at bay, I imagine that in the Third Temple, may it be built speedily in our days, no raven chasers will be needed.
Test render of iron spikes covering the Sanctuary Building.
The top of the wall will eventually be covered with spikes as well.

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