134 ANNUAL OF SCIENTIFIC DISCOVERY. 



doors and of the " follower," giving to the latter a parallel motion while press- 

 ing, by means of toggle-levers. A- clear explanation of the principles of the 

 press can not be given without engravings, but it is sufficient to say that the 

 press is portable, easily taken down and put together, and inexpensive. In 

 short, a farmer, instead of being obliged to build an expensive structure as 

 formerly, can now order a hay-press with as much facility as he can a reaping- 

 machine or a horse-power. 



THOMPSON'S CIRCULAR SELF-ACTING GATE. 



A patent has been recently granted to William Thompson of Nashville, 

 Tenn., for an improved peculiarly self-acting gate. The invention relates to 

 gates for farms, parks, and iuclosures of any kind, and consists in constructing 

 the gate of a circular form like a wheel, and allowing it to rest, when closed, 

 on a vibrating rail which is operated by a person, wagon, or carriage on the 

 track, to make the gate roll to the one side and open when approaching it, 

 and then roll back when the carriage or wagon has passed through to close 

 it. This lever railway is hung upon a pivot, with its long end toward the 

 opening of the gate, so as by its weight at that end to tilt down the gate into 

 its place, self-acting, when the lighter end is relieved from the weight or 

 pressure of a carriage, etc., on the roadway, after it has passed through. The 

 platform, or track which is connected with the lever, may be provided with 

 any suitable fastening, such as a spring switch with a vertical lever at one side, 

 which will set free a catch on the platform, and allow it to act so as to pre- 

 vent animals opening the gate by merely getting on the platform. 



There is claimed for this gate great simplicity of construction ; and when 

 its cheapness, utility, and beauty (if desired) shall be remembered, and it is 

 likewise borne in mind what little skill is required to make it, and how little 

 its liability to get out of repair, it is believed that it will be regarded as prefer- 

 able to the common gate swinging on hinges ; and may possibly be esteemed 

 superior to any form of gate among the various inventions of more modern 

 date. 



THE GREAT INDUSTRIAL EXHIBITION AT PARIS. 



One of the most memorable events in the scientific history of the past year 

 has been the Great Industrial Exhibition of Paris. In many respects it was 

 far in advance of the London Exhibition of 1851. " Every one," says the 

 London Practical Mechanics' Journal, " who compares the two Exhibitions 

 must perceive a decided advance since 1851 in almost every branch of manu- 

 facture ; and we think that the Paris Exhibition must be held to afford a more 

 complete and accurate idea of the state of the industrial arts of the present 

 day, than did our Exhibition of the state of the arts of that day." There were 

 several distinct parts of the Exhibition having separate buildings near each 

 other. First, the exhibition of the fine arts, containing a wonderful collection 

 of more than 2,000 paintings, the works of painters now living or lately 

 dead, as well as a great number of pieces of sculpture, engravings, etc., amount- 

 ing in all to 5,112 works of art. Secondly, the " Palace of Industry,'' and 



