Adjustable level
BRIEF DESCRIPTION OF THE INVENTION 
     Field of the Invention 
     Levels comprising elongate members with one or more flat surfaces and one or more bubble housing(s) with visible floating bubbles and guide markers to indicate with the bubbles when the flat surface or surfaces are level have long been known and used. Such levels are used for a great variety of purposes and are particularly useful to carpenters, bricklayers, sheet rock installers, fence and siding installers and others in the building trades such as electricians, plumbers, and pipefitters. In fact, such levels are also frequently used by anyone installing or working with pipe, conduit, steel, studs, electrical boxes and appliances. 
     Many types of levels have been proposed in the past. One such level is shown, for example, in U.S. Pat. Des. No. 317,725. A level, sold under the tradename &#34;LEVLIT&#34;, as early as October 1991, included rubberized magnets attached to the inner surfaces of the legs of an angled base; a bubble housing with a bubble therein adjustably secured to an outer surface of one leg of the angled base; and ruler indicia marked on the outer surface of the other leg of the angled base. A &#34;VELCRO&#34; strap is attached to the angled base for use in securing the &#34;Levlit&#34; to a structure. Locking of the bubble housing with respect to the base is provided using a threaded post projecting from the bubble housing through the leg of the base and a wing nut threaded onto the post. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Objects of the Invention 
     Principal objects of the present invention are to provide an improved adjustable level having an angled base with magnetized legs that will magnetically attach either the inner surfaces or the outer surfaces of the legs to magnetic surfaces, and that has positive locking of the bubble housing at small angular rotations of the bubble housing relative to to the angled base on which the housing is mounted. Another object is to provide an adjustable level wherein angular adjustments betweem bubble housing and base can be made quickly and easily, without diassembly of component parts. 
     Features of the Invention 
     Principal features of the invention include a plurality of spaced apart spot magnets spaced along the length of each leg of an angled base; the use of meshing radial members on a leg of the base and on a bubble housing, respectively; together with locking means to lock the bubble housing to the base leg in a pre-set position. 
     The locking means comprises a mounting post and a spring surrounding the post and biasing a bracket on which the bubble housing is mounted into locking engagement with the base. 
     Additional objects and features of the invention become apparent to those skilled in the art to which the invention pertains from the following detailed description and claims. 
    
    
     THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of the adjustable level of the invention mounted to a pole; 
     FIG. 2, a vertical section view of the adjustable level taken on a line 2--2 of FIG. 1; and 
     FIG. 3, an exploded perspective view. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings: 
     In the illustrated preferred embodinent, the adjustable level of the invention, shown generally at 10, is attached to a pole, shown generally at 11, by a retainer 12. 
     The level includes an angled base 13, having legs 15 and 16 projecting normal to one another from a junction 14. The overall length of the base 13 can be as desired, but generally will not be less than about six inches so that a reliable level measurement can be obtained. 
     The retainer 12 includes a flexible cord 18 having one end fixed to a coil spring assembly 18a inside a housing 19. The housing 19 is fixed to an outer surface of a leg 15 or 16 of base 13. A loop on the other end of cord 18 engages a hook 19a on the housing 19. The cord 18 is pulled from housing 19, against the bias of the spring assembly 18a, by the loop 19a and is adapted to be passed tightly around a structure, and then to have the the loop 19a connected to the hook 19b. The spring assembly 18a in the housing 19 holds the cable tightly around a structure. The retainer 12 thus allows the level 10 to be securely attached to a structure and to be used even while the user has both hands free, as needed, for purposes other than holding the level. 
     Spot magnets 20 are inserted into each leg 15 and 16 and are spaced along the length of each leg. As shown, three spot magnets are inserted in each leg, but the number of spot magnets used will depend on the length of the base 13. Each spot magnet extends fully through the leg in which it is inserted and the exposed opposite surfaces of the magnets are flush with the inner and outer surfaces of the legs. The spot magnets 20 are positioned to be close to the outermost edges of the legs in which they are inserted so that they will securely grip round poles or other curved surfaces to which the level 10 may be attached. 
     A bubble housing 30 is fixed to an outer surface of one leg 31 of an L-shaped bracket 32. The bubble housing is of conventional construction and includes a transparent plastic housing 33 filled with a suitable liquid and with a bubble floating in the liquid. Parallel markings 34 on the housing and degree markings 35 around the periphery of the housing allow a user to determine if a leg 15 or 16 of the level is level or the extent to which such leg is out of level. 
     The outer surface of the other leg 36 of bracket 32 has a pair of narrow ribs 37 and 38 extending opposite to one another from a hole 40 through the leg. The ribs 37 and are each adapted to fit snugly into one of a series of grooves 39 formed in the outer surface of a leg 15 or The grooves 39 radiate from a central post 41 extending through the hole 40 in leg 36 and each have a length just longer than the length of the ribs 37 and 38. The grooves 39 are equiangularly spaced and the number of grooves 39 provided determines the amount the bubble housing can be turned with respect to the leg 36 between positive locking of the bubble housing 30 to the base 
     The bubble housing 30 is positively locked to the leg 15 when the ribs 37 and 38 are positioned in oppositely extending grooves 39 by a compression spring 50 that fits around the post 41 extending from base 13 through the hole 40 in the leg 36 of the bracket 32. As shown, post 41 is threaded into base 13. Post 41 has a head 52 thereon and the spring 50 fits between the head 52 and leg 36 of the bracket 32 to bias the leg 32 and bubble housing 39 thereon towards the base 13 and the ribs 37 and 38 into grooves 39. 
     A ring 36a located inside the ribs 37 and 38 fits into a ring circular groove 36b on the leg 15 that is positioned inside the grooves 39 to guide the bracket as it turns with respect to the base. 
     In practice, the user merely pulls the bracket 32 from the base 13 while compressing the spring 50. The bracket 32 is then rotated about the post 51 until the desired angular relationship between the bubble housing 30 and the base 15 is established. The bracket 32 is released and the spring 50 biases the bracket into locked relationship with the base. The bubble housing is thus positively locked to the base at a desired angle. 
     An indicator marker 70 on the leg 36 of the bracket 32 aligns with the degree markings provided on the leg 32 of the base to allow a user to set a desired angular relationship between the bracket and the base. 
     Although a preferred form of our invention has been herein disclosed it is to be understood that the present disclosure is by way of example and that variations are possible without departing from the subject matter coming within the scope of the following claims, which subject matter we regard as our invention.