ern boundary of the National Zoological Park and Connecticut Avenue, from Cathedral Avenue to Klingle Road, this land, together with the included highways, to become a part of the park. The appropriation was not a continuing one and lapsed at the end of one year, before legal proceedings for the purchase were completed. Items for the reappropriation of this sum and for the additional amount necessary to meet the figures fixed by the court in proceedings of condemnation have since been submitted to Congress in the estimates each year, but have not been favorably considered. The principal entrance to the park will always be from Connecticut Avenue, and the importance of a frontage on that thoroughfare at and bordering the gate can not be overestimated. The necessary land should be acquired before it is too late, in order that when the time comes a dignified entrance gate can be constructed and the nearby land controlled by the park authorities. IMPORTANT NEEDS. Roads, bridle paths, and automobile parking.-As mentioned in the report for last year, the question of providing space for the parking of automobiles near the main buildings is serious. The enormous increase in the number of cars visiting the park makes it difficult to care for the safety of the public without adequate parking space. More than 4,500 automobiles sometimes pass through the park in a single day, and many of the large sight-seeing cars regularly visit the Zoo. During the coming year it will be necessary to make extensive repairs to roads and walks, and some change should be made in the bridle path in order that riders would not be forced to use the bridge and main road from the Harvard Street gate to the cross roads. Grading and filling.-As soon as practicable the work of grading and filling, commenced two years ago but discontinued for lack of funds, should be completed. As left, it makes an unsightly and unfinished-looking place in one of the most conspicuous points in the park bordering the main road. The further cutting away of the irregular hill in the center of the western part of the park and the filling in of the near-by ravine will level nearly 70,000 square feet of ground which is now of little use and make available a further 25,000 square feet of ground at the ravine. This will eliminate a dangerous curve in the automobile road. Repairs to antelope house.-Practically the whole west side of the antelope house needs reconstruction. The building is over 20 years old and the timbers and other woodwork on the west side are almost beyond repair. When the work is undertaken the walls should be fixed properly with concrete and the cages considerably enlarged. It is estimated that an expenditure of about $2,000 will be necessary to put this building in good condition. Adams Mill Road grade and stairway.-The work of grading Adams Mill Road between Clydesdale Place and Harvard Street, recently commenced by the District, will make necessary some expenditure on the part of the park to care for the resulting fill above the stairway and walk leading into the park from the Adams Mill Road gates. At present it is impossible to estimate the exact amount of work that will be needed, but it is probable that a new bridge and walk will have to be built at one point, with a substantial retaining wall at the base of the fill for the safety of the public. A very narrow strip of land between Adams Mill Road and the park, from Clydesdale Place to Ontario Road, still in private ownership, should be added to the park for the protection of this point. Additional lake for waterfowl.-Exhibits of waterfowl are among the most popular and instructive features of the park. An additional lake, to be used for the birds in summer and for skating in winter, could be built at comparatively small expense on the open flat near the Harvard Street entrance. Aviary building.-The need of a new house for the exhibition of birds has been felt for some years and is becoming more pressing because of the greatly increased numbers of visitors now cared for in the park. Such a building should be provided with commodious public space. The aisles in the old bird house are far too narrow for the crowds of the present day, and the exhibition of birds, important and valuable as it is, can not be properly displayed. Reptile house.-A public exhibition building, properly constructed and equipped for the display of reptiles and amphibians, would be greatly appreciated by visitors. The small collection of reptiles now kept in inadequate and wholly unsuited quarters in the lion house is very popular. The reptile house should be planned to show in natural environment the various types of reptiles of economic importance, those sought and used for food, and those feared by man in many countries. The educational value of such a building could be developed to a point of great importance. Outdoor quarters for mammals.-Many species of mammals, especially some of the larger carnivores, now kept in cages in heated buildings, could be much better shown and more pleasantly and healthfully located in outdoor quarters with warm but unheated shelters. A large African lion, kept in the park for two winters without artificial heat, has shown marked improvement from such treatment. Such provision should be made for the exhibition of certain of the lions, the Siberian tigers, and other mammals. Outdoor cages, adjoining the winter quarters, should be constructed on the east side of the lion house for the leopards, jaguars, and hyenas. The unsightly row of cages along the crest of the hill north of the bird house should be replaced by new sanitary yards with comfortable but unheated retiring quarters attached. Owing to the great increase in the number of people who take advantage of the recreational and educational features of the park, the necessity for a substantial increase in the appropriation for regular maintenance expenses is apparent. For the safety and comfort of the public the number of policemen, attendants, keepers, and caretakers must be augmented, as the force now maintained is not greater than was considered necessary when the attendance was barely half its present figures. Respectfully submitted. N. HOLLISTER, Superintendent. Dr. CHARLES D. WALCOTT, Washington, D. C. APPENDIX 5. REPORT ON THE ASTROPHYSICAL OBSERVATORY. SIR: The Astrophysical Observatory was conducted under the following passage of the sundry civil act approved June 12, 1917: Astrophysical Observatory: For maintenance of Astrophysical Observatory, under the direction of the Smithsonian Institution, including assistants, purchase of necessary books and periodicals, apparatus, making necessary observations in high altitudes, repairs and alterations of buildings, and miscellaneous expenses, $13,000. For observation of the total eclipse of the sun of June eighth, nineteen hundred and eighteen, including purchase of necessary apparatus and supplies, transportation of equipment to and from observing station, hire of temporary assistance, transportation and subsistence of observers, and miscellaneous expenses, $2,000. The observatory occupies a number of frame structures within an inclosure of about 16,000 square feet south of the Smithsonian Administration Building at Washington, and also a cement observing station and frame cottage for observers on a plot of 10,000 square feet, leased from the Carnegie Solar Observatory on Mount Wilson, Cal. Its equipment comprises special optical, electrical, and other apparatus adapted to measure radiation of the sun, the sky, and terrestrial Much of the apparatus has been built at the observatory instrument shop on the Smithsonian grounds in Washington according to designs of the director. The instrument maker, Mr. A. Kramer, has been employed by the observatory nearly 30 years in this experimental construction work, and his experience and skill, added to his natural ability, render him invaluable. New designs are continually being worked out as new experiments are being made. The present value of the buildings and equipment is estimated at $50,000. This estimate contemplates the cost required to replace the outfit for the purposes of the investigations. Owing to the highly specialized character of the apparatus no such value could be obtained at public sale. WORK OF THE YEAR. At Washington.-As heretofore the work of measuring and computing from the records obtained in the field on Mount Wilson has gone on steadily in charge of Mr. F. E. Fowle, aided by Miss F. A. Graves, computer, and Mr. R. Eisinger, messenger. Mr. Fowle completed and published1 his investigation of the absorption of long wave rays by long columns of air containing known quantities of water-vapor. His results give the relations between absorption and atmospheric humidity, wave-length by wave-length, from the visible spectrum down to waves of more than 20 times the maximum visible wave-length, and for quantities of water ranging from to three times that which prevails in the vertical thickness of the atmosphere above Washington in clear spring weather. Many difficulties which were met required tedious subsidiary investigations which are described in the paper. Notwithstanding the greatness of this contribution to meteorological science the subject of the relations of water-vapor and terrestrial radiation demands yet more investigation adapted to cover the range of wave-lengths from 16 microns to 50 microns, where Mr. Fowle was forced to give over the investigation temporarily, because no substance suitable to make a prism for forming the spectrum of these rays was known. Mr. Aldrich has since investigated at the observatory a great number of natural crystalline and other substances, including many pure chemical preparations. None was found appreciably more transparent than rock salt, which was used by Mr. Fowle, except potassium iodide. Apparently this substance, if it could be procured in large crystals, or fused into a noncrystalline structure, would be suitable to carry the work to much longer wave-lengths. Efforts have been made, as yet unsuccessfully, to procure blocks of this substance of suitable proportions and inner structure for making large prisms. Mr. Aldrich has carried on a number of investigations on the absorption and reflection of atmospheric-water-vapor, liquid water, lampblack, gelatin, and other substances to rays emitted by a blackened reservoir filled with boiling water. In these experiments he has employed rock salt transmission plates to roughly separate the total radiation into two parts, whose wave-lengths are respectively greater and less than about 20 microns, where rock salt ceases to be transparent. The results on water-vapor agree well with what Mr. Fowle's spectrum work would tend to indicate. They also show that an atmospheric layer about 50 meters deep, containing watervapor equal to 0.05 centimeters of precipitable water, would probably absorb all the rays sent out by the 100° C. radiator which are nontransmissible to rock salt, that is above the wave-length 20 microns. This is in harmony with observations of the sun and of nocturnal radiation made by Mr. Aldrich on Mount Wilson, to which reference. 1 Water Vapor Transparency to Low-temperature Radiation. Smith. Misc. Coll., Vol. 68, No. 8, 1917. |