First, let me say that I consider it a great privilege to be asked to do this study of the wood in this very special staircase. I have to say, also, that I, for many years, have stood in awe while viewing this most wonderful work of art and mechanics which required the very greatest skill a man could possibly attain with his hands and mind. Therefore, I have approached this study with a totally open mind, unbiased, and with the utmost honesty.
During my formal training as a scientist, it was impressed upon me very
early that one absolutely must eliminate all personal feelings and
bias from a study in order that it be truly a scientific study. So in that
light, this work was carried out. The report itself is written in third
person, as it should be. However, I chose to write this preface in
first person thereby adding the warmth and personal mood so necessary here.
BACKGROUND. As a child, I grew up in New Mexico and came to be a part of the culture and people of the area. Religion was always a part of my background since my parents were both very good Christians and God was always present in our home. Our family always traveled together and made many trips to visit the old missions and towns around the state. Santa Fe was always the most fascinating and had the most, I thought, to draw me back; as a magnet draws a piece of iron unto itself.
During the very early fifties, I had the pleasure of being the guest of the Sisters of Loretto Academy and was told the entire story and history of the academy, the chapel and the "mysterious" staircase. I always found the story of "that little man" appearing to offer his efforts to provide the sisters with a long-needed staircase to the choir balcony very interesting and, in my case, entirely believable. You see, I have always believed in miracles, but usually examine the situation to determine just how the miracle was performed, or, if in fact, it is actually a miracle. However, it is not the purpose of this paper to determine whether or not the building of this staircase was a miracle, but to attempt to identify the wood used therein and to investigate the physics of the support mechanism. At a later date, a mathematical model and physical model shall be constructed and this report will be amended to include the findings thereof.
I shall not endeavor to repeat the story here, but I advise the reader to refer to the publication The Inexplicable Stairs written by Sister M. Florian, O.S.F.
I had the privilege of having a personal tour, one-on-one, of the premises
and especially of the chapel and staircase. We spent most of an afternoon,
the Mother Superior and I, in the chapel and on the staircase and
in the choir loft. I got an excellent opportunity to experience first hand
the reverence of that most holy place. The entire chapel has a definite
aire of peace, and holiness, and the very presence of God is truly felt--even
to this day ! My most favorite spot in the chapel is sitting in the pew
just under Jesus' statue where He looks directly into my eyes. One can
feel His love penetrating to the very center of one's being.
TECHNICAL. As to structure of the staircase, it comprises two complete revolutions (720 degrees) in its entire height which sits on a reinforced floor and is attached at the top to the choir-balcony joist with wooden pegs. The design of the staircase is that of a double spiral connected with steps. The "double spiral" comprises two wood stringers each constructed in a spiral form, however, the inner stringer (spiral) is almost two and a half feet smaller than the outer stringer (spiral). In this type of design, the inner stringer which spirals on approximately a one-foot radius, is of such small radius that the stringer acts as a very stiff spiral (or spring, if you will). (Note: The measurements I state here are only approximate and are not to be taken as accurate, but are used only for explanation of a structural principal.) In other words, it functions in a structural situation as as almost solid cylinder of wood (as would a wooden "pole").
However, the outer stringer (spiral) is of much larger diameter, but it does not exceed, by very much, the mathematic limit of self-support for a spiral under full load which is determined by the material from which it is made. (I.e., wood being of lesser compressive and tensile strength than steel, but steel having a much different "bending moment" than wood..) In other words, these things are key to determine the strength of a spiral structure.
In this instance, the staircase does have a central support and can, in deed, support itself and a considerable load of people. The central support is the inner spiral that is of very small radius which functions as an almost solid pole. Further, the structure is strengthened by the outer stringer being attached to the inner stringer by the steps about every six inches. These steps are of triangular shape which is consistent with the mathematical divisions of a circle (radians) which add even more distribution of loading stresses. Also, the outer stringer is stiffened greatly by these steps which provide paths for forces to be transmitted to the inner stringer which is much stiffer. Finally, the steps provide many rigid braces arranged in a circular fashion spirally thus forcing the outer and inner stringers to collectively function more or less equally and simultaneously.
The springiness felt when walking on the staircase is the result of the wood's reaction to the amount of loading being applied with respect to the wood's fixed "bending" characteristics. Technically, the "bending moment" mentioned here is the point at which the wood's shape remains changed when a side load is applied to its longitudinal axis, and is the definition used here.
Actually, if one will notice carefully, the springiness is a bit more
on the outer ends of the steps than on the inner ends of the steps. This
differential of springiness is due to the larger diameter of the outer
stringers being able to spring a bit more because the angle of leverage
with respect to the horizontal floor allows for more "give" or bend in
the wood. This would, most likely, prevent the "outer" stringer from standing
alone. This, also, therefore, is the reason from an engineering standpoint,
the steps are fastened so accurately and carefully and strongly to both
SUMMARY. The Inexplicable Stairs can be explained, however it remains a "mystery" to we humble humans just how they got there and who built them. But I hasten to add this: No matter who built them, God Himself had a major hand in it. The wisdom, the knowledge of carpentry and cabinetry, the mighty skill of hands are all items of total mastery of the trade. I, myself, served my apprenticeship and came to graduate as a master cabinetmaker prior to entering university at age thirty. I mention this only to lend credibility to the forgoing statement, and to say that I would be very challenged to construct such a staircase using the tools and transportation of the time. However, if the occasion should ever arise to do such a thing, as in all other things I do, I shall trust that He will give me the things I would need to do the task; I am not at all surprised nor do I doubt that this is truly a "miraculous" staircase.
This is truly a fine example of excellent engineering and craftsmanship
and should be contemplated by all thinkers of our time and times to come.
This work published by Forrest N. Easley. All rights reserved.
No part of this work may be copied or reproduced by any method or means
whatsoever without written permission of the author. All rights of translation