2. A prize of two thousand dollars for the most satisfactory essay upon (a) the known properties of atmospheric air, considered in their relationships to research in every department of natural science, and the importance of a study of the atmosphere, considered in view of these relationships; (b) the proper direction of future research, in connection with the imperfections of our knowledge of atmospheric air, and of the connections of that knowledge with other sciences.
3. A prize of one thousand dollars for the best popular treatise upon atmospheric air, its properties and relationships (including 
Comparative Areas of Zoological Parks. those to hygiene, physical and mental). This essay need not exceed twenty thousand words in length; it should be written in simple language, and be suitable for publication for popular instruction.
4. The Hodgkins medal of the Smithsonian Institution will be awarded annually, or biennially, for important contributions to our knowledge of the nature and properties of atmospheric air, or for practical applications of our existing knowledge of them to the welfare of mankind. The medal will be of gold, with a duplicate in silver or bronze.
The treatises may be written in English, French, German, or Italian, and should be sent to the Secretary of the Smithsonian Institution before July 1, 1894; except those in competition for the first prize, which may be delayed until December 31, 1894. The time was subsequently extended to December 31, 1894, for all prizes.
Provision was made in the circular for a committee of award, for extending the dates above named, and for modifying the conditions prescribed. The circular also stated that special grants of money will probably be made to specialists engaged in original investigation upon atmospheric air and its properties.
