Ig20.] Scientific Intelligence. 73 



monlv observed results. Should we adopt the gauge recorn- 

 mended by Mr. Kerr, it would be necessary to construct a scale 

 of the surface at every degree of the rain's inclination, as it will 

 be observed that the maximum of surface will be when the rain 

 inclines in an angle of 45°, and the minimum when either hori- 



zontal or vertical. . . 



If the saucre were shaped like a funnel, it would m a great 

 de-ree privent the effect of height or exposure, or the quantity 

 of ?ain collected, because the impinging current would be inclined 

 to the smaller end of the cone; and little, if any, would be 



disposed to pass over the top. , , c-- 



I have the honour to be, near feir, 



Your most obedient humble servant, 



Thomas Holt. 



XIII Further Remarks on propelling Vessels hy Windmill Sails. 



By Mr. Bartlett. 



(To Dr. Thomson.) 



Buckingham, h on. \.,\'i\'i. 



Permit me to point out the following errata which appear in a 

 note fpp 339, 360, of your number for the present month) to 

 my pTp^er On the Propulsion of Vessels by Means of WindmiU 

 sJik, which you did me the honour of copying into your ^«««/.. 

 They' arise from the incorrect manner in ^^Ivxh the decima s are 

 pointed off, viz. 4,021,248 square feet should be 402 1 24» , 

 670 008 X 32 = 21,446,656 lbs. 670-208 x 32 =21446-656 ; 

 and' 128,679,936 lbs. 128679-936; the three right hand figures 

 of each quantity being decimal fractions. i,:^!, „nn 



The note was thus erroneously printed in the work which you 

 extracted it from ; but, as the product of those """^^ers wa. 

 correct. I did not think it necessary to notice the mistake, until 



^"^^u r^mrkYafthl- idea itself '' is not new," it Wg been 

 « proposed nearly a century ago ; " in reply to ^v-hich, I beg to 

 observe, that it can certainly lay but little claim to ongnabty 

 beino- nothing more than the application of one power to the 

 mechanical impulsion of another; in other words, impar jng 

 momenta to the machinery of steam-vessels by means of wind- 

 mill sails. But, if I am not mistaken, you allude to the plan ot 

 Bishop Willdns for impelling land carriages, v/h^ch I conceive, 

 both in its construction and application, to be ,^^dely different 

 from the one I propose. I did not know, until long after 1 had 

 submitted my ideas upon the subject to the world in a separate 

 treatise (which afterwards appeared in the Pamphleteer), that 

 such a suggestion had been made as to the PO««;b'l'ty />| 

 moving carnages on wheels by means of revolving sails ; and 1 

 liave yet to learn that it had ever been proposed so to impel 



floating bodies. . ^^:„.r' ihfk 



The idea first suggested itself to me upon witnessing the 



