330 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[August, 



the semicircle c dh, and bisect it with a perpendicuhir line a d, and 

 from d set oft' the chord of any angle between 45 and 6 



1 60 degrees, as 



df, and from / draw a perpendicular to the base line c h, then_/e is 

 said to be the sine and f d the cosine, of the required angle. The 

 width of the floats should not, it is said, in any part exceed the s'lnefe. 

 Figs. 2 and 3 in the annexed diagrams show two side views of a 

 propeller having the floats fixed at an angle with the shaft in the form 



Fig. 4. 



Fig. 6. 



of a cone, the apex of which is foremost, or next to the stern of the 

 boat. Fig. 4 shows an end view of the propeller, and shaft in sec- 

 tion. Fig. 5 shows an end view of a similar propeller, but having 

 three floats or vanes in place of two. Fig. 6 is a side view of a pro- 

 Fig, c. 



peller, the floats or vanes of which are of the form of a parabolic curve, 

 A, being the stern of the boat with a portion of the dead wood re- 

 moved for the reception of the propeller, which will be clearly under- 

 stood. 



The inventor claims the attaching blades or propellers to ships at 

 tangents coincident with the plane of ;i right cone placed longitudi- 

 nally with the apex foremost; and also the employment of blades of 

 the form of parabolic sections, whether attached to the shaft at tan- 



gents coincident with the plane of a right cone placed longitudinally 

 with the apex foremost, or in a position parallel to the same. 



LOCKS AND LATCHES. 



William Fletcher, of Moreton House, Buckingham, Clerk, for 

 " Improvements in the construction of locks and latches applicable for 

 doors and other purposes." — Granted January 30 ; Enrolled July 30, 

 1844. 



This invention for improvements in locks and latches applicable to 

 doors and other purposes, will be understood by the following descrip- 

 tion and reference to the annexed drawings ; fig. 1 being a front view 



Fig. 1. 



of a lock with one side removed, so as to show the interior ; and fig. 

 2 a transverse section of the same ; a is the bolt of the lock, which is 



Fig. 2. 



pressed outwards by a spring b, which presses against the end of the 

 bolt; c is a lever or tumbler moving upon an axis c', d d is another 

 lever moving upon an axis d', the lower end of this lever when the 

 bolt is shot drops into a notch or recess formed in the bolt, the upper 

 end supporting the end of the levers c ; the lock contains three 

 pair of these levers, which are divided or separated by plates, e, which 

 plates are shown in section at fig. 2, and form wards to the said lock ; 

 //, fig. 2, are the door handles fixed at each end of the spindle g, 

 which spindle is made with two inclined planes shown in dotted lines, 

 these inclined planes act against a small roller, i, fixed to the bolt, a, 

 by means of a screw, which screw forms the axis of the roller; it will 

 therefore be seen that on pressing either of the handles towards the 

 door, or by pulling the same in an outward direction, that one of the 

 inclined planes will press against the roller, i, and draw the bolt back 

 inwards; that is to say when the levers or tumblers have been raised 

 from the notch formed in the bolt a ; the action of this lock, therefore 

 is as follows : — 



If the key be inserted and turned one-fourth of a revolution to the 

 left hand, the upper end of the lever, d, will be forced back, and in so 

 doing will raise the lower end out of the notch formed in the bolt a, 

 the end of the lever c at the same time drops into a notch cut out of 

 the end of the lever d, and prevents the lever d from falling into its 

 original position ; the whole of the levers being in like manner acted 

 upon by the difterent projections of the key ; the bolt may then be 

 drawn back, or inwards, by forcing or pulling at one of the handles as 

 above described; the levers will now bi> in the position shown by 

 dotted lines, and in order to lock the door, it will only be necessary to 

 shut the same, and having inserted the key, then by turning it round 

 either to the right or left llie various projections will raise the levers, 

 c, and allow the levers, d, to drop into the notch formed in the bolt, a. 



