34.7 x 12.6 x 35.5
Brass
CAT. 1824 : H.I.74
Machina rotatoria, que se poem em movimento pela rotação dos vapores da agoa.
Tem em cima um carrete, que communica com uma roda dentada, para mostrar o
modo como se poderia aplicar a acção dos vapores, como força mechanica. Esta applicação é do Sr. C.B.de L.Lobo. Jornal de Coimbra.
A rotating machine that is set in motion by the rotation of water vapour. It has a carriage on top that communicates with a gear, in order to show how it is possible to apply the action of the vapours as a mechanical force. This application is that of Sr. C. B. de L. Lobo. Jornal de Coimbra.
In an article published in the Jornal de Coimbra entitled "Memória sobre o novo methodo de aplicar ao movimento da máquina a força de vapor d'água fervendo", ( Report about the new method of applying the force of boiling water vapour to the movement of the machine), which is the transcription of a report read at the public session of the Academia Real das Ciências de Lisboa on 18th January 1805, the professor of the Gabinete de Física Experimental, Botelho de Lacerda, presented a proposal to improve the steam machine.
The article says that his machine constituted a development of the instrument described in chapter 27 of volume II of Musschenbroek's work entitled Introductio ad Phylosophiam Naturalem. According to Musschenbroek, a copper cylinder, movable around its vertical axis, having two lateral tubes in its upper part with two small holes diametrically opposed, could be made to rotate if it were filled with a quantity of water to a third of its capacity. The movement would start when the water, on being heated, started to boil, some of the steam escaping through holes made in the lateral tubes of the cylinder.
This demonstration was made every year by Botelho de Lacerda in the Gabinete de Física during his lessons. According to this teacher, the demonstration described in Musschenbroek's book did not have any other aim than to entertain or amuse the people present.
For the improvement of this device, Botelho de Lacerda suggested the fitting of a cogwheel, or a worm-screw to the upper part, allowing the connection with any other rotating machine, thus obtaining a continuous circular movement through a simple and economic process. Botelho de Lacerda adapted a pulley to his machine. A string passed through the pulley in order to raise a body. This string was wound on a horizontal rotating axle of a cogwheel, which engaged with a second wheel that moved together with the machine's cylinder.
The preparation of a model based on the project developed by Botelho de Lacerda was the job of J.B. Haas, the maker of the exemplar in the Gabinete de Física. The following inscription can be read on this machine: J. B. Haas, Lisboa.
Lobo, Constantino António Botelho de Lacerda, "Memória sobre o novo methodo de aplicar ao movimento da máquina a força de vapor d'água fervendo", Jornal de Coimbra, Coimbra, 1812, vol. 1, p. 255.