1818.] Scientific Intelligence. 75 



his house in Dover-street, with a magnificent present of plate 

 for his acceptance. The inscription, which is engraved on a 

 massy silver waiter, records the services for which it was given. 

 " To John Ayrton Paris, M.D. F.L.S. Fellow of the Royal Col- 

 lege of Physicians of London, this plate is inscribed by the 

 noblemen, representatives in Parliament, and gentlemen of the 

 county of Cornwall, in testimony of their grateful sense of his 

 services, in originating the plan, and promoting the institution of 

 the Royal Geological Society of the county, which has rendered 

 their home the school of science, and their native riches increas- 

 ing sources of prosperity." 



VI. On the Spiral Oar. By James Boaz, Esq. 



(To Dr. Thomson.) 

 SIR, Glasgow, June8, 1818. 



In your Annals of Philosophy for this month, I see a paper 

 signed by Mr. T. L. Dick, stating that Mr. Scott, of Ormiston, 

 had shown him a drawing of a spiral oar for propelling a vessel. 

 As I consider this kind of oar may be brought to do much good in 

 that way, I beg leave to state that the same occurred to me on 

 August 12, 1804, which was the day after I had been foiled in 

 an experiment by another method for propelling a small boat (on 

 the Hugginfield Loch) used at building the wooden bridge over 

 the Clyde here. I soon after made a model of a boat on a small 

 scale, with two strong clock springs in one barrel, to drive a train 

 of wheels, which wrought one of these spiral oars inside of a 

 double keel at the bottom of the vessel, having gratings to pre- 

 vent weeds from getting foul of the oar. I tried various sorts of 

 spiral, some with the thread very close, others more sparse, and 

 a few with two, three, and even four threads. I was best pleased 

 with that having a double thread and moderate angle, as the 

 motion of the model in the water at an experiment, Nov. 2, 1804, 

 was at the rate of from four and a half to five miles per hour. 

 This, if necessary, I can produce credible witnesses to testify. 

 Whether the idea was new on August 12, 1804, I know not — 

 it was so to me. 



A spiral has since, under my direction, been successfully 

 applied to force hot air into a cold apartment where there was 

 power to spare for driving it ; and 1 have often thought that 

 the principle, if properly executed on a large scale, might m some 

 cases be used for ventilating coal and other mines so as to free 

 them of dangerous gases. Your obedient servant, 



James Boaz. 

 VII. A new Metal. 



We are informed that Prof. Stromeyer, in examining the subli- 

 mate which concretes in the chimnies of the zinc furnaces of 

 Saxony (and which has long been known to chemists by the name 

 of Cadmiu fornacum), has discovered a new metal, to which he 

 has given the name of Cadmium. Of this we hope to be able to 

 give a further account in our next number. 



