Art. 91. The exemptions from duties shall be given by the custom houses in Belém and Manáos, by a requisition from the Minister of Agriculture, from whom it shall be requested, attaching to the request a memorandum of the objects with specification of the qualities, quantities and ends for which they are needed, and what are imported for the services of the first establishment, and after this what must be imported for its maintenance. Art. 92. The enterprise shall be subject to inspection by the Government as to the safety of the steamers, and processes employed in fishing, the faithful use of the objects imported, the manufacture of preserving, in which substances hurtful to the public health shall not be employed, nor in the annual production of preserved or salted fish for the purpose of obtaining the premiums in money. Art. 93. Specimens of fish not well known, the party shall send one properly preserved to the Minister of Agriculture, accompanied by a small relatorio describing the place and conditions under which it was caught and noting anything particular that might be interesting in studying it. Art. 94. Every commander or master of the vessels of the enterprise, shall make a written communication to the directors for them to bring to the knowledge of the Government, the places where there is the existence of any obstacle to navigation, indicating the position in a good sketch of that stretch of the river, describing its nature and the route to be followed to avoid it. These communications shall be transmitted to the Minister of Transportation in order that he may place a signal on the obstacle, and as soon as possible remove it. TITLE VI The Triennial Expositions Embracing All That Relates to the National Rubber Industry Art. 95. The Rubber Expositions shall be held in Rio de Janeiro every three years, the first being on May 13, 1913; its object shall be to give the sum of the triennial movement of the national rubber industry in its various modifications, compared with the industry in other countries. Art. 96. The triennial expositions shall include the rubber industry in all its branches and shall include the following classifications: 1. The Culture. 2. The Extraction. 3. The Improvement. 4. The Manufacture of Articles. The classes shall be subdivided into groups including native and cultivated plants, machinery, utensils, processes, commercial type, studies and statistics. Art. 97. Premiums of encouragement shall be given for the best processes of culture, extraction and treatment, and to the best manufactured products, whether as raw material, constituting commercial types for exportation, or as to manufacture. Art. 98. The Government shall opportunely request the National Congress for the necessary enactments to make these premiums effective.