# Popular Science Monthly/Volume 64/April 1904/The Air of the Luray Caverns

Layout 4
* THE AIR OF THE LURAY CAVERNS.
By GUY L. HUNNER, M.D.,
THE JOHNS HOPKINS UNIVERSITY MEDICAL SCHOOL.
AT Luray, Page County, Virginia, is located a health resort which represents an idea unique in hospital or sanitarium construction. The dwellers in Limair may keep their doors and windows closed summer and winter, and still breathe air as pure as that of the mountain side.
My acquaintance with this institution began in the fall of 1901, when making a vacation drive through the Shenandoah country. After a ramble through the Luray Caverns, our party was shown through the sanitarium and treated to the novel experience of living in the caverns' air, while enjoying a full measure of light and sunshine.
Limair has an elevation of about one thousand feet above the sea level. It stands on a hill about two hundred feet above the neighboring water courses, and commands a magnificent view of the Page Valley with the enclosing mountain ranges—the Blue Ridge to the east and Massanutten range to the west. These mountains are from three thousand to four thousand feet high, and as seen from the elevation in the center of the valley they present a panorama of never-failing interest. The Page Valley is said to enjoy more sunshine than can be elsewhere found in the United States east of the Rocky Mountains. A pine forest of about one hundred and forty acres which covers the Luray Caverns hill affords beautiful walks and drives, and is not the least of the attractive features of the place, when considered as a health resort.
Mr. T. C, Northcott, builder and proprietor of Limair, is a heating and ventilating engineer of twenty years' experience, and he has devoted many years to the problem of establishing an institution that would combine the advantages of sunlight and beautiful surroundings with an air supply at once voluminous and pure. After investigating the caves of New York, Ohio and Virginia he secured building and park privileges over the Luray Caverns as a site comprising the greatest number of healthful and attractive features. A reference to the photographs (Figs. 2 and 3) will give an idea of how well the site has been chosen. The drawing (Fig. 1) explains the methods of air supply and ventilation, but only a visit to the institution will demonstrate how completely the theories of the engineer are being worked out in practical results.
At my first visit, in the fall of 1901, I saw demonstrated the remarkable volume in which the air enters and leaves each room without creating appreciable draughts, and the fact that the air is practically free from atmospheric dust. Tyndall ('Lectures on Dust and Disease') has shown that if we darken the ordinary room and allow a streak of sunlight to enter, the condition of the atmosphere revealed is such that ​we can not without repugnance step into the illuminated area and breathe. Such an experiment in a room in Limair reveals scarcely a particle of dust floating in the air; i. e., the air is optically pure. Noting this fact, I became interested in the bacteriologic condition, and determined to visit Luray again, supplied with culture media and sterile plates.
In December, 1902, fitted out with five dozen sterile plates and six dozen tubes of agar-agar, I spent four days at Luray studying the bacteriologic conditions in the caverns, sanitarium, out of doors, and in neighboring homes. My plates were prepared by being wrapped in separate paper covers, sterilized in dry heat and transferred to a box still wrapped in their paper covers. The agar-agar was in separate tubes stoppered as usual with cotton plugs. Each morning before starting in quest of bacteria the required number of fresh plates were prepared. That my technic was entirely satisfactory was demonstrated by setting a closed control plate at each place where other plates were exposed. The readings from the plates were made after incubation for twenty-four hours at 85 degrees F. On the first day the exposures and results were as follows:
1. In the caverns: Three plates in Vegetable Garden, 50 yards from entrance; plates exposed five minutes and one hour and the control plate were all negative.
Three plates at Crystal Spring, 100 yards from entrance; on plate exposed five minutes, two colonies; plate exposed 50 minutes, negative; the control plate, negative.
Three plates at Skeleton Gorge, 200 yards from entrance; 5 minutes, 35 minutes, and control, all negative.
Three plates at Cathedral Room, 300 yards from entrance; 5 minutes, 30 minutes, and control, all negative.
2. In the air passage between the cave and the house (see Fig. 1) four plates were exposed for one half hour as follows: Plate 1, at the mouth of the air shaft coming from the caverns. A; plate 2, in the beginning of the long auxiliary condenser, D, just beyond the fan; plate 3, at the other end of the auxiliary condenser; plate 4, on the floor of the plenum, where the air rushes down from the condenser. On none of these plates was there any growth.
3. In the sanitarium three plates were exposed for respectively 5, 20 and 60 minutes in each of three rooms, viz., the library on the first floor; a guest chamber on the second floor, not used for the previous week; and in a bedroom on the second floor, in constant use. The morning work had been done in this latter room one hour before my plates were placed on the bed. One colony on the five-minute plate, and three colonies on the 60-minute plate in this room, and two colonies on the hour plate in the library were the only results from these nine plates.
​On the evening after my first day's work, the daughter of the household gave a party to about fifty young people of Luray, and on making my first examination of the plates, I was so astounded at the results that I immediately prepared more plates, thinking that enough dust and dirt would have been left in the house on the previous evening materially to alter results. I was even more surprised after exposure of plates for two hours in the library, reception hall and game room, to find the most contaminated plate to contain only nine colonies. This was the plate exposed on the mantle shelf immediately above a large open fireplace in the reception hall, between the hours of eleven and one o'clock noon, when the household of about six people was moving about as usual on a winter morning.
Plates were set for two hours in the caverns on the second day at the same places as on the first day. Again two colonies developed on the plate exposed near the Crystal Spring, while the other plates were negative.
For the sake of comparison, and to learn whether all houses in that vicinity contained unusually pure air, I exposed a plate in the house of a well-to-do farmer within a mile of Limair. The house was scrupulously neat and clean. The plate was exposed for one hour on a mantle-shelf back of a heating stove in the sitting room, where five or six people were passing in and out. In other words, the conditions were about the same as those under which nine colonies developed after a two-hour exposure at Limair. After 24 hours of incubation 143 colonies were visible on this one-hour plate.
In a physician's office at Luray 92 colonies were implanted in one hour. I expected to catch more bacteria in a physician's office than in a farm-house, and the difference may possibly be explained by the location of a large, open fireplace opposite the door entering from the street, thus affording a means of constant ventilation, with repeated additions of fresh air from the outside.
Fig. 2. Limair Sanitarium, Luray, Virginia. Notice the absence of roofed verandas. Large sun rooms occupy the south side of the sanitarium. Massanutten Mountains just visible in the distance.
Fig. 3. View from Sun Parlors of Limair Sanitarium, Luray, Virginia. Luray one mile distant. Blue Ridge Mountains beyond.
​a twenty-five minute trip from Broadway to Lafayette Avenue, showed over 1,600 colonies after a thirty-six-hour incubation at 85° F. Plates exposed for one hour in the surgical and gynecologic operating rooms at the Johns Hopkins Hospital showed, respectively, 65 and 58 colonies after incubating 48 hours at 100 degrees. These comparative studies are suggestive, and the studies in the caverns and sanitarium demonstrate that with optical purity or freedom from atmospheric dust, we have air that is practically free from bacteria.
But in spite of the bacteriologic purity of the air in Limair Sanitarium, I am sure many will protest against breathing the polluted, moldy emanations from a source never penetrated by the rays of the sun. I must confess this was my first impression, and the same prejudice has been expressed by many friends with whom I have conversed. But what are the facts, and what is the condition of the caverns' air? In the first place the air is not stagnant. In any part of the caverns the guide's candle, if placed on the floor or on the ledge of a wall, shows by the deflected flame a very decided current of air. Owing to the differences in temperature, there is a constant interchange of air between the caverns and the outside world. This circulation takes place through many natural filters distributed over the hillside in the form of crevices in the rock, which have become filled by porous soil. Both air and water are cleansed in passing through these earth filters. If there be any open fissures for the admission of unfiltered air, its organic particles would soon be deposited on the damp caverns' walls. The action of water passing over and causing the slow dissolution of such a vast surface of limestone can not but be ​beneficial to the caverns' air. It would be trite to dwell on the advantages of lime as a purifier and disinfectant.
Again, we find no organic matter in the caverns undergoing decomposition, and have on every hand the beautiful, clean, limestone walls and draperies being corroded and reformed by the constant action of myriads of water courses (see Fig. 5). Can we arrive at any other conclusion than that here we have the purest and cleanest atmosphere that can anywhere be found?
Mr. Northcott 's control of the temperature and humidity conditions is a feature over which the thoughtful visitor must grow enthusiastic. The temperature of the caverns registers from 54° to 56° F. throughout the year, and the relative humidity varies but a fraction of a per cent, from 87. In the hottest summer weather the sanitarium temperature
ranges from 70° to 74° F., and the relative humidity is reduced to 70 per cent, or less, merely by the expansion in volume incident to an increase in temperature from 56° to 70°. In the winter the air is easily raised in temperature from 54° to 70°, and the problem of humidity, while somewhat more complicated than in the summer, is perfectly controlled. As seen in Fig. 1, the air is sent through a boiler-like box of sheet iron (B) and comes in contact with a wide surface of iron tubing, the opposite surface of which is exposed to the cold air outside. This one box failing to reduce the humidity sufficiently, there was built a long sheet-iron passageway (D) over the summer air corridor, and by placing a closed door (R) the air is forced through this accessory condenser to be still further robbed of its moisture.
​Dr. Wm. C. Bailey, who is doing such excellent work with consumptives at Las Vegas, N. M., informs me that the yearly average of humidity at his altitude is 40 per cent. The average at Denver is about 50 per cent, at 70 degrees temperature. When we consider the great and rapid changes of temperature at such favorable locations, and think of the wide range of relative humidity experienced even in the course of one day, we see at once that the engineer at Limair, starting with his great caverns of air of a uniform temperature, and uniform percentage of relative humidity, has a simple problem to solve in keeping the sanitarium at an equable temperature, and in what is considered the normal percentage of relative humidity. Attempts are now being made to furnish hospitals and large public buildings with these desirable conditions of a dustless, cool air, of uniform temperature and humidity; but while the problem is theoretically possible, the outside conditions are such as to make the undertaking one of such expense as to be impracticable.
The practical side of this question from a therapeutic view-point appeals to those familiar with throat and lung diseases. For hay fever, asthma and all bronchial affections, not tuberculous, these conditions are ideal, and for patients of this class have already given excellent results. We can not imagine conditions better calculated for the preservation of infant health during the hot summer months, when the rapid atmospheric changes of our cities play such havoc with their powers of resistance to intestinal infections.
We now know the relatively minor rôle that the tubercle bacillus plays in the destruction of the consumptive patient, and the great advantage of placing the early tuberculous process in an air free from dust and the secondary bacterial invaders. We know how injurious to some patients are the climatic changes of a sea voyage, or of the seaside resort, and how badly others react to a change of altitude. Here we have an abundance of cool, pure air rapidly circulating in sunny rooms easily kept at constant conditions of temperature and humidity. Consumptives are not taken at this sanitarium, but I think it is only a question of time when those afflicted with tuberculosis of the air passages may enjoy the benefits to be derived at Luray and other caverns of the world by living in houses modeled after Limair.