NFW BOILER. 5 



degree of correctness, and the naturalist might delineate 

 minute objects in any degree magnified. 



Since the primary intention of this instrument is already, 

 in some measure, answered by the Camera Obscura, a com- 

 parison will naturally be made between them. 



The objections to the Camera Obscura are 



1st. That it is too large to be carried about with con-Comparison 

 TCnience. of the camera 



. lucida with the 



The Camera lucida is as small and portable as ean be camera ob- 



wished. scura - 



2dly. In the former, all objects that are not situated 

 near the centre of Tiew are more or less distorted. 



In this, there is no distortion ; so that every line, even 

 the most remote from the centre of view, is as strait as 

 those through the centre. 



3dly. In that, the field of view does not extend beyond 

 30° or at most 35 a with distinctness. 



But in the Camera Lucida as much as 70° or 80° might be 

 included in one view. 



As it has been thought advisable to secure an exclusive 

 sale of this instrument by patent, those who are desirous of 

 purchasing it are informed that Mr. Newman (No. 24 Soho 

 Square) has at present the disposal of it. 



II. 



Description of a new Boiler constructed with a View to the 

 saving of Fuel. By Benjamin Count of Rumford. 

 Read at a Meeting of the first Class of the National In- 

 stitute the 6th October, 1806*. 



XT is well known that much is gained in the saving of fuel, Boiler for 



when an extensive surface is given to that part of the boiler generating 



., *. . steam ; having 



against which the name strikes, but this advantage is often i ts bottom tec- 

 counterbalanced by great inconveniences. For a boiler of mmating in 

 the form usually employed, having the bottom very much 

 extended in proportion to its capacity, must necessarily 

 present a great surface to the atmosphere, and the loss of 

 heat, occasioned by the cold air coming in contact with 



* Translated by W. Caddel Esq. and revised by the count, 

 from whom it was received, 



this 



