US906680A - Base for surveying instruments. - Google Patents

Description

G. L. BERGER.

BASE FOR SURVEYING INSTRUMENTS.

APPLICATION FILED MAR. 31, 1905.

906,680. Patented Dec. 15,1908.

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mamwm m. {W L- i w W w w w CHRISTIAN L. BERGER, OF BOSTON, MASSACHUSETTS.

BASE FOR SURVEYING INSTRUMENTS.

Specification of Letters Patent.

Patented Dec. 15, 1908.

Application filed March 31, 1905. Serial No. 253,032.

To all whom it may concern:

Be it known that I, Crnns'rmiN L. Banana, a. citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented an Improvement in Bases for Surveying Instruments, of which the following description, in

connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

In certain situations, as for instance in mine surveying, it is frequently impossible to employ the usual tripod support for the different surveying lllStl'Llll'lBlll'S on account of the low stoping or special condition which makes it impossible to set up the instrument in the usual manner, and accordingly the head of the instrument is commonly removed and placed on a beam or other ledge and sometimes on the ground, being held in position sometimes by a screw-ring or base, and at other times by a trivet or tribrach, the latter heretofore consisting simply of three small legs extending inwardly and upwardly to a threaded ringlike center for receiving the threaded end of the ii'istriunent-head.

My invention resides in providing a trivet having a broader base than the instrument itself provides, and carrying adjusting means whereby the instrument may be freely turned and shifted without disturbing the trivet, until it is centered with the plumb bob (usually hung overhead in such work).

A further object of my invention is to provide great stability and certainty of posi tion by means of the trivet.

In the drawings, Figure l is a perspective view of the preferred embodiment of my invention, showing a portion of a surveying instrument in operative position thereon; Fig. 2 is a top plan view of the trivet repre senting the adjustments thereof in dotted lines; and. Fig. 3 is a vertical, sectional view taken on the line 33, Fig. 2.

It will be understood that by the term trivet. I do not intend to limit myself to three legs, but use the word, as commonly used, to mean a rigid, low'base or support.

As herein shown I provide three branching diverging legs a, a, 66-, each having a short pointed end or foot a depending from the narrow outer end of the leg proper, the latter rapidly thickening as indicated at (0, until it joins a heavy central cylindrical cup-shaped hub 54'' containing a central, vertical, cup-shaped cavity. At its upper end the entire trivet is provided with a plane surface u, corresponding in general outline to the legs and hub and overhanging the latter. as clearly indicated in the drawings. Said legs have their lower and upper sides extending respectively from the bottom portion of said hub and from the outer portion of the plane top of the trivet and thence converging toward the outer ends of 'the legs, and each leg also has its opposite upright sides converging towards its top and diverging from the outer end of the leg along its bottom portion to the hub, whereby the leg is broader at its bottom side than in its upper portion. and is wider and heavier at the hub than at its outer end. The hub a has a narrow, inwardly extending flange at its under side and a threaded annulus a at its upper side. Resting on the plane top a is a ring 7) having three projecting arms 1) which is perfectly free to shift in any direction on the flat top a. Cooperating with the threaded annulus a is a threaded nut b for clamping and retaining the instrument and shifting ring 7) stationary having a laterally extending cap or flange I) titting flat against the smooth top surface of the ring Z), the latter having an internal opening considerably larger than the nut b, as clearly shown in Fig. 3. For convenience the nut 7) is provided with wings 5*, whereby it may be quickly turned into clamping engagement with the ring D or loosened therefrom as desired so that when loosened, the ring Z) may be shifted axially or in any other direction, as indicated in dotted lines in Fig. 2.

Depending through the nut b which is provided for the purpose with an opening If, is a stem (3 internally threaded at its upper end at c to receive the usual threaded end (Z of the inst rument D and threaded at its lower end at to receive a star nut c for adjusting the instrument in clamped relation. with the trivet or base-support which constitutes my invention. The stem c has a 'llange c for preventing its dropping through the trivet when released from the instrument and the star nut c carries a hemispherical. bearing 0 bearing in a plate 1; adapted to engage the under side of the hub a when the instrument is tightened in place. At its lower end the stem 0 carries a thumb nut for turning the entire stem so as to screw the threads 0 upon the threaded end (Z of the instrument.

At their outer ends the arms I) are provided with sockets b and centering slits b for receiving the ends of the usual adjusting screws (Z of the instrument, whereby the latter is leveled in usual manner. Instead of locating said centering slits b, as shown, they may be placed centrally in the top surface a of the trivet, as shown at (4", Figs. 2 and 3, when the trivet is used with instruments which do not require the shifting adjustment for which the shifting ring Z) is provided, the idea being simply to provide a centering means or positioning slit which will maintain the lower ends of the adjusting screws in unalterable relative position.

In both embodiments of my invention, the plane top surface which extends laterally integrally from the hub, supports the ad justing screws of the instrument head, said screws being supported thereby in direct contact with the slits a when no shifting movement is required, and said screws being supported thereby for free shifting movement by being mounted in direct con tact with the slits b of the interposed shifting ring when shifting is required.

In use the instrument head is removed from its regular tripod and is placed on top of the trivet, its adjusting screws being centered either in the slits b or a (the former being required for a transit, for example, and the latter for a leveling instrument). Thereupon the stem 0 is rotated by its end a into threaded engagement with the part (Z of the instrument-head and is then clamped to the trivet by rotating the star nut If the instrument is a transit or the like, the cap-like nut b is first loosened, before attempting the above centering operation thereby permitting the entire instrument to be shifted with the supporting ring 71 in any direction, and when it is finally brought into absolutely correct position, it is secured and clamped in the manner above set forth.

My invention enables the surveying instrument to be placed solidly on the ground or timber low down so as to occupy very little space and yet the trivet base is broad, extending laterally beyond the instrumenthead supports or adjusting screws 4, so as to provide against accidental tipping, and the construction is such that the trivet is not only broad but heavy and stable, while yet permitting all the adjustments and precision of position which have heretofore been secured in the ordinary tripod construction as used on the surface where the operator has been able to stand upright and manipulate his instrument with freedom of movement and position. My object is to obtain the same results in the cramped, limited space of a low stoping or drift, or the like, in mine work.

I do not intend to limit myself to all the details of construction herein set forth, as

my invention is capable of many other embodiments within the spirit and scope of the following claims.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A trivet for surveying instruments, having a central hub provided with an opening extending through from top to bottom,

and adjustable means extending vertically through said hub for retaining the instrument-head, said trivet having plane top surface extending laterally integrally from said hub for supporting the adjusting screws of the instrument-head, and short, rigid and branching legs beneath said top surface and immovable with relation thereto.

2. A trivet for surveying instruments, comprising a. heavy central hub having a plurality of integral legs extending radially and all lying in approximately a horizontal plane, said legs and hub being thick and heavy for giving stability of position to the instrument and having their top surfaces flat, horizontal all in one plane and adapted to permit sliding movement in all directions of a superposed flat part, to sustain the adjusting screws of the instrument, and provided with a center vertically open from top to bottom and means cooperating with said center for retaining the instrument-head rigidly thereon.

A trivet for surveying instruments, having central means for retaining the instrument-head, a plane top surface extending laterally co-exteusively of the entire top of the trivet for supporting the adjusting screws of the instrument-head, radial centering grooves formed in said plane top surface for said adjusting screws, and short, rigid and branching legs beneath said top surface.

l. A trivet for surveying instruments, comprising a rigid, low support having branching legs, a central retaining device for clamping the instrument-head fast against lateral movement, and means for shifting the instrument laterally of said legs without moving with it said central retaining device.

5. A trivet for surveying instruments, comprising a rigid, low support having branching legs, a central clamp for clamping the instrument-head fast against lateral movement, and shifting means for said 1nstrument head provided with means for receiving in unvarying position the adjusting screws of the instrument-head, said shifting means being capable of shifting the instrument and said adjusting screws laterally of said legs in all directions without shifting said central clamp.

6. A trivet for surveying instruments, comprising a rigid, low support, having a heavy central hub containing a central vertical cup-shaped cavity with a narrow inwardly extending flange at its under side and a threaded annulus at its upper side, branching legs extending laterally from said hub and terminating in short pointed feet.

7. A trivet for surveying instruments, comprising a rigid, low support, having a heavy central hub containing a central vertical eupshaped cavity, laterally branching legs extending from said hub, said trivet having a plane top surface extending laterally from said hub to receive the superposed parts of the surveying instrument and permit the lat ter to be shifted freely thereon in all directions. said legs having their lower and upper sides extending respectively from the bottom portion of said hub and the outer portion of the plane top of the trivet and hence converging toward the outer ends of the legs.

8. A trivet for surveyinginstruments, comprising a rigid, low support, having a heavy central hub containing a central vertical eupshaped cavity, laterally branching legs extending from said hub, said trivet having a plane top surface extending laterally from said hub to receive the superposed parts of the surveying instrument and permit the latter to be shifted freely thereon in all directions, said legs having their lower and up per sides extending respectively from the bottom portion of said hub and the outer portion of the.plane top of the trivet and thence converging toward the outer ends of the legs, said terminating in lntegral dependlng stub-like pointed feet.

9. A trivet for surveying instruments, com

prising a rigid, low support, having a heavy central hub containing a central vertical cupshaped cavity, laterally branching legs extending from said hub, said trivet having a plane top surface extending laterally from said hub to receive the superposed parts of the surveying instrument and permit the latter to be shifted freely thereon in all direc tions, said legs having their lower and upper sides extending respectively from the bottom portion of said hub and the outer portion of the plane top of the trivet and thence converging toward the outer ends of the legs, each leg also having its opposite upright sides converging toward its top and diverging from the outer end of the leg along its bottom portion to the hub, whereby the leg is broader at its bottom side than in its upper portion and is \vide' and heavier at the hub than at its outer end.

' In testimony whereof. l have signed my name to this specification, in the presence of two subscribing witnesses.

Cl-llll i T [AN ll. l3 EliGEl-t. \Vitnesses GEO. H. lvlaxwnim, ,M. A. Jones.

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