Here is a link to an undated photo of a Texas & Pacific freight yard:
If you zoom the photo and look to the left you'll see a Santa Fe refrigerator car with Garland ventilators on its roof. This car may be either a Class Rr-O or
Rr-P reefer. Some cars in both classes were equipped with Garland ventilators. The photo probably was taken in 1908 or later as that is when some Rr-O reefers received the Garland ventilators as a retrofit.
Use these links to view an illustration of this device and another roof photo from a wreck scene:
Below are two early industry articles about Garland ventilators.
From The Railway and Engineering Review, Volume 48
February 22, 1908
The Garland Car Ventilator
The question of ventilation of passenger car equipment has been given increasing prominence recently, and several discussions of the subject have brought out the paramount importance to the passengers of an adequate supply of fresh air. Systems and devices in considerable variety have been advocated to accomplish this end, some of them impractical, some inefficient, and some well calculated to meet the end in view. The Garland ventilator which has been before the railroad public for about three years seems to be of this last class, and it has now met with so wide an introduction that a description of the device and its principles of operation will be of some interest.
Tills ventilator is the invention of T. H. Garland, general agent refrigerator service, Chicago, Burlington & Quincy R. R. at Chicago, and it is handled commercially before the market by the Garland Car Ventilator, 902 Medinah building, Chicago. In its form and the method of applying it, the ventilator is inconspicuous and compact...
Application of Garland Ventilator to Refrigerator Cars.
The slightest investigation into the handling of fruits, vegetables and other perishable freight In refrigerator cars will reveal the necessity of providing better car ventilation. Hundreds of carloads of berries, peaches, oranges and other fruits are damaged every year on account of Insufficient ventilation in refrigerator cars. The upper tiers in the cars become soft or moldy, due to the warm air and gases that accumulate In the upper part of the car and have no means of escape or being drawn off. Roads handling this class of traffic are called upon to pay thousands of dollars each year on account of poorly ventilated refrigerator cars. To prevent these heavy losses and enable the roads to get shipments through to destination in good condition, an efficient ventilator is a prime necessity.
The construction of the ventilator as applied to this use is practically the same as that for passenger equipment...
The ventilator is applied to the roofs of refrigerator cars in the center of the car between the doors...
According to the claims of the Inventor anemometer tests have shown that when the car Is running at a speed of thirty miles per hour, a ventilator of the size shown in the illustrations is capable of exhausting 10,000 cu. ft. of air per hour from the car. As the refrigerator cars thus far equipped have each two of these ventilators, it follows that the total exhaust may be 20,000 cu. ft. per hour. If the car body contains 2000 cu. ft. of air, which is approximately correct, this would mean that all the air in the car would be exhausted ten times per hour. A damper or regulator is provided at the inner end of the opening into the car, so that the ventilation of refrigerator cars can be regulated according to the requirements of the load.
For two years refrigerator cars equipped with this ventilator have been in service. The many tests made are said to show that the warm air and gases that gather In the upper parts of the cars are all drawn off by the ventilator. When cars are under ice the warm air and gases are forced by the cold air from the ice tanks to the center and upper part of the car and remain there unless drawn off at that point by ventilators. The results with ventilation show that when cars are under refrigeration, the same, or nearly the same temperature can be maintained in the upper part of the car as at the bottom. By producing good refrigeration throughout the car, the losses mentioned are prevented.
Ice & Refrigeration
A new refrigerator car with heating and ventilating apparatus was exhibited at the La Salle Street railway station, Chicago, the last week of February. The distinctive feature of this car is that underneath the removable slatted floor of the car are rows of piping through which the meltage from the ice flows in warm weather, adding thus to the refrigerating service of the ice in the bunkers, while in cold weather exhaust steam from the engine is admitted and serves to keep the contents of the car from all danger of injury by frost. The pipe is so trapped that the ice water or the steam, as the case may be, is automatically ejected after the purpose has been accomplished. It requires no attention except connection of steam inlet with the steam line of train. Moreover in the ceiling of the car are two openings about a foot square each, provided with beveled stops and connecting on roof of car with a Garland ventilator (described in former issues of ICE AND. REFRIGERATION). These ventilators are opened or closed from the car roof by a lever suitably marked. The car has thus a combined refrigerating, heating and ventilating apparatus, which takes up no extra space within the ear and requires exceedingly little attention and no skilled attention. The ventilating features coupled with the refrigeration from the ice water in the pipes beneath the slats on the floor, result, it is claimed, in securing an equable temperature in all parts of the car. The device is the invention of T. H. Garland, refrigerator car traffic manager of the Burlington railway system, who was also the inventor of the Garland ventilator, which is now extensively used in both passenger and freight cars.