Pick from the Past
Natural History, November-December 1923
Mounting Horse Skeletons to
NOT SO VERY LONG AGO the osteological exhibition in a museum was merely a collection of sets of bones carelessly put together. No attention was paid to scientific mounting of the skeleton nor was any attempt made to express the living animal in action. As a result these exhibits defeated the very purpose for which they existed. They offered no incentive to the student or to the public even to visit, much less to study and make comparisons between, the different types of animals represented.
For instance, to convey to the spectator, through the mounted skeleton of a horse, some idea of the nicety of adjustment of every bone, and the positions assumed by it in relation to other bones during pulling, racing, trotting, and walking, is no easy task, and before accurate results are achieved, an amount of study, patience, and care is required little dreamed of by the casual observer.
For more than twenty years Mr. S.H. Chubb, of the department of comparative anatomy in the American Museum, has devoted all his attention to revolutionizing osteological preparation of Museum specimens. In the Museum collections is a nearly completed series of mounted skeletons of the Equidae in which Mr. Chubb is striving to represent with scientific accuracy and in lifelike pose every possible type of horse. There is a giant draft horse and, from practically the same stock, although representing another breed, the Shetland pony. The big horse has been developed through many generations for extreme size, whereas the Shetland pony has been reduced in size by mans selection and breeding. A heavy type of horse is shown in the position assumed when drawing a load. In contrast, there is the remarkable horse Sysonby, known as one of Americas most famous race horses, beautifully mounted to show the running gait characteristic of his kind. The pure-blood graceful Arabian,
Lee Axworthy, raised on the walnut Hall Farm in Kentucky, was owned by the Pastime Stable, a concern consisting of four or five men, and was stabled at Castleton Farm, Kentucky. The American Museum is largely indebted to Mr. D.M. Look, of New York, owner of Castleton Farm, for the skeleton of this famous trotter. Mr. Chubb is finding the mounting of the skeleton of Lee Axworthy a most interesting study, as it give the opportunity to compare the bones brought into action in the fast trot with those employed in the more natural running gait of the race horse Sysonby.
A slight idea of the painstaking care with which every contributing detail is studied and worked upon until scientific accuracy is attained, may be gained from some of the activities in connection with the preparation and mounting of the skeleton of Sysonby. To represent properly the changing curves of the spine of the race horse when he is running his fastest, Mr. Chubb conceived the idea of making photographic studies of a race horses back in action. Accordingly an arrangement of ropes was prepared and fastened at one end to the roof of the American Museum and at the other to an adjacent tree. A swinging seat suspended from the rope and steadied by guy ropes afforded an unobstructed vantage point for the accommodation of Mr. Chubb and his camera. A race horse was borrowed for the occasion. Certain points of the animals anatomy. Previously determined upon by Mr. Chubb as best marking the constantly changing curves of the spine and the shifting of the muscles in action, were outlined with white patches which would be clearly visible in the photograph. Even the shadow of the horse cast by the sun at right angles was taken into consideration to help portray in profile the position of the horses feet and body at the moment of exposure. All being ready, Mr. Chubb was hoisted fifty feet above the ground, and the horse was raced back and forth below him while he took photographic studies of the horses back.
This new and unusual method of photography, also used in the case of the Lee Axworthy skeleton, resulted in a series of studies which
There is much to be done from the moment the skeleton is dissected to the time the bones are finally mounted. Sometimes these tasks are very time-consuming; eleven months were required to prepare the skeleton of Sysonby for exhibition.
The writer had an opportunity to witness a part of the preparation of the skeleton of the trotter Lee Axworthy, listening the while as Mr. Chubb explained the process in progress at the time. Mr. Chubb was seated at a long table busily engaged in scraping from the sternum of the skeleton fragments of flesh and soft tissue that still adhered to the bone. Near him on the floor were several jars containing water in which were immersed various parts of the skeleton.
I save the sternum or breastbone for the last, he said, because it requires more time. The bones are connected with ligaments and tendons which must be removed before the actual cleaning and dryin can proceed. To hasten the decomposition of the soft tissues, the bones are placed in vessels containing water that is kept at 100 degrees.
When sufficiently decomposed the ligaments and tissues are removed and all that remains after dissecting is scraped away as clean as possible. If the surface of the bone dries too rapidly, it contracts and splits, while the inside is still wet. Slow drying is preferable and will prevent such injury by permitting the entire substance to dry evenly. The next step is to free the bones completely from all grease, that they may become spotlessly clean and pure in color before they are articulated.
Immersing the bones in benzine and exposing them while in this medium to daylight and sunshine for a number of weeks will accomplish the desired result most successfully. Under Mr. Chubbs supervision tanks have been constructed of galvanized iron. Around the upper edges of each tank are special grooves into which slides a close-fitting cover of glass, effectively sealing the tank against the entrance of rain water and at the same time preventing evaporation of the benzene. The bones are put in the tanks and covered with benzine, the glass covers are moved into place, and the tanks are then carried to the roof of the Museum, there to remain in the sunshine until the bones are pronounced ready for the next step. The benzine must be changed two, three, or possibly four times during this period, because it becomes saturated with the grease and loses its efficacy, and the bones easily get discolored, gummy, and dirty if left too long in the greasy benzene. The whole process may take from six to eight weeks, depending on the amount of sunshine and the size of the bones.
After the benzine process, said Mr. Chubb, the bones are ready for mounting. First, I get a steel rod as nearly as possible fitting the opening and extending the length of the neural canal of the spinal column. This rod I must shape to the curve of the spine. Then the vertebrae are hung tentatively in place. Next, I gradually study the bones of the legs, which I fasten together temporarily so that any change can easily be made in the angle of the joints. The legs are suspended by looped cords passed over the heads of small screws, which are inserted in the bones at various points. The other ends of these cords are passed several times over horizontal rods above. To these free ends are attached small weights sufficiently heavy to prevent slipping, thus affording easy and convenient adjustment. Now comes the delicate task of getting the bones into the position which seems to suggest the action I have in mind, and seems to do it in a perfectly alive and satisfactory way. Getting the ribs in position is a long operation. I take a very small piece of pliable steel rod and fasten to it the several ribs, each by means of a rubber band. Then I study the little articulations. Finally, when they are all satisfactorily placed, I devise a permanent brace to fit the ribs and hold them enduringly in place. Every step, meanwhile, is checked up and corroborated by constant comparison with a great number of photographs.
As I get the adjustment nearer and nearer perfection, I see errors in this part or that which were not obvious when the bones as a whole were out of position. It is simply a process of eliminating the errors until the whole becomes perfect. When all is right, I drill small holes where the bones come in contact with each other, and into these holes drive steel wires just tight enough to hold firmly but not tight enough to break the bone. Where there are many little bones, wires are driven in from opposite directions to bind all together as firmly as possible. These wires are driven down just a little below the surface of the bone, and the small holes which result from this operation are filled up later with plaster.
In studying the trotting modifications found in the skeleton of Lee Axworthy Mr. Chubb remarked that these might possibly be found in a race horse, but they were not evident in the skeleton of the race horse Sysonby. On the front pastern (but not in the hind) of the skeleton of Lee Axworthy was a slight depression in the bone due to extreme movement of the pastern joint in the trotting action. Said Mr. Chubb, I can imagine that this might become adaptive and prove of great advantage in that particular action, but we cannot say that it has gone far enough at present to be of great consequence.