| 1. An Act to Adjust and define the rights of the Texas & Pacific Railway Co., May 2nd, 1873 |
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Whereas, By the terms and conditions of an act entitled "An act to encourage the speedy construction of a railway through Texas to the Pacific Ocean," passed May 24th, 1871, and an act supplementary and amendatory thereto, passed November 25th, 1871, authority was given to the Southern Trans-Continental Railway Company, and to the Southern Pacific Railroad company, incorporations created by acts of the Legislature of the State of Texas, to become consolidated with the "Texas Pacific Railroad Company," an incorporation created be an act of the Congress of the United States; and Whereas, It appears from documentary evidence on file in the office of the Secretary of State of the State of Texas, that such consolidation has been effected; and as a difference of opinion may arise as to the construction of the acts of the Legislature hereinbefore referred to, in regard to the amount of lands to which said Texas and Pacific railway Company may be entitled under the said acts of incorporation, and other laws of this State; and Whereas, It is desirable that there should be a complete and final adjustment of the rights of said Texas and Pacific Railway Company, as the assignee and successor of the said southern Pacific Railroad Company, and the said Southern Trans-Continental Railway Company, under the laws of this State, and a definitive understanding as to the obligations of the State, and to the further end that said company be encouraged to the speedy construction of said railway; therefore, Section 1. Be it enacted by the Legislature of the State of Texas, That the "Texas and Pacific Railway Company," a corporation created by an act of the Congress of the United States as the successor of the "Southern Trans-Continental Railway Company," a corporation created by an act of the Legislature of the State of Texas, approved July 27th, 1870, shall construct its road from the town of Marshall, in Harrison county, to the city of Jefferson thence in a northerly direction to a point in Bowie county, not exceeding six miles west from Texarkana, at which point of intersect with its main line, which shall be constructed from or near Texarkana, on the Arkansas line, through the towns of Clarksville, Paris, Honey Grove, Bonham, and to Sherman. by the first day of July, 1874; thence through the towns of Pilot Point and Denton to the point of junction with the Southern Pacific railroad line at fort Worth, by the first day of January, A.D. 1875, and shall erect passenger and freight depots within one-half mile of the business portions of said towns; provided, said towns respectively shall donate to said company the necessary lands for right of way, side tracks, switches and depot buildings, not to exceed, in each case, twenty acres; provided, that said depots shall be erected in the towns of Bonham, Sherman, Pilot Point and Denton, upon the grounds now agreed upon and donated to said railroad company by said towns; and provided further that said railway company shall commence the grading of their railroad in the county of Denton within ninety-five days from the passage of this act, and shall continuously prosecute the same until the said road shall be graded between the towns of Sherman and Fort Worth. And the said Texas and Pacific railway Company, as the successor of the "Southern Pacific Railroad Company," a company created by the laws of the state of Texas, shall construct its road from its present western terminus at Longview, in Upshur County, as now located through the town of Dallas, to the point of junction at Fort Worth by the first day of July, 1874; and said Texas and Pacific Railway shall construct a single track railroad from the said point of junction at Fort Worth westwardly, on the most practicable route, to a point not less than one-fourth nor more than one-half mile from the courthouse in the town of Weatherford, in Parker county, at which point said company shall establish and maintain a freight and passenger depot; provided, it shall not be obligatory upon said company to go by said town and establish said depot in the event the said town of Weatherford fails to give said company, free of charge, twenty-five acres of land, the same to be designated by the said company, for the purpose of depot buildings, track, sidings, switches and turnouts and also give, free of charge, the right-of-way through the said town, and a tract of twenty-five acres of land situated on the line of said railroad and within one and a half miles of the court house in said town and thence westwardly on the most practicable route to the Rio Grande river at a point in the county of El Paso, opposite the town of El Paso, in Mexico and said single track railroad shall be constructed from the said point of junction, at Fort Worth, at the rate of one hundred miles per annum, until it reaches the Rio Grande river provided, said road shall be completed and put in running order to the main line of the trans-continental road near Texarkana, or from such point on said line as the railroad now being constructed from Little Rock to a junction with said trans-Continental road, may cross the Arkansas State line, the same not being more than seven (7) miles north of Texarkana, by January, 1874, and shall build and maintain a depot within one-half mile of the town of Clarksville, in Red river count. Sec. 2. That the State of Texas hereby grants and donates to the said Texas and Pacific Railway Company twenty sections of land, of six hundred and forty acres each, for every mile of its road completed in good substantial running order in the State of Texas; that is to sat, on the branch road from Marshall to Jefferson, by August 1873, and from Jefferson to the main line of the Southern Trans-Continental road, in Bowie county, and from or near Texarkana, or to the point of junction of the trans-continental road on the Arkansas State line with the railroad now being constructed from Little Rock, thence to Fort Worth, and from Longview to Fort Worth, and from Fort Worth to the Rio Grande river, opposite El Paso, in Mexico; provided, the said road shall be constructed from Marshall by Jefferson, on the line hereinbefore designated, to Sherman, by the first day of July, 1874, and the grading be commenced in the county of Denton, within ninety days from the passage of this act, and be continuously prosecuted until the said grade is finished between Sherman and Fort Worth, and the road completed and put in running order to Fort Worth buy the first day of January, 1875; and the road from Longview to Fort Worth shall be completed and put in running order by the first day of July, 1874; and the road from Longview to Fort Worth shall be completed and put in running order by the first day of July, 1874; and the single track road westward from Fort Worth to the Rio Grande, after the first day of January, 1875, shall be constructed and put in running order at the rate of one hundred miles annually and further provided, that should said company fail to complete either of its said lines within the manner and time hereinbefore prescribed, to the point of junction, it shall thereafter forfeit all right to any donations of land or reservation of lands, except upon its completed road and should said company fail to construct its single track westward from the point of junction at Fort Worth, in the time required, it shall forfeit all its rights to donations or reservations of land, except upon the portion thereof completed provided, that in no case shall the State be in any way liable for deficiency of vacant domain. Sec. 3 That whenever and as often as said Texas and Pacific Railway Company shall complete an put in running order a section of ten miles or more of either line of its road, or of its single track road, as hereinabove designated, said company shall give notice thereof to the Governor of the State, and it shall be his duty to appoint some skillful engineer, if there be no state engineer, to examine said completed road, and make report thereon, under oath, to him; it shall then be his duty, if the same is shown to have been constructed in accordance with its charter, and as required by law to report the fact to the Commissioner of the General Land Office; thereupon, it shall be the duty of the Commissioner of the General Land Office to issue to said company twenty certificates for six hundred and forty (640) acres of land for each and every mile of road so completed. That all land certificates that shall issue to said company under the provisions of this act, shall be located and surveyed, in alternate sections; that is to say, said company shall cause to be surveyed two sections of six hundred and forty (640) acres each, for each certificate adjoining, and shall return to the General Land Office the field notes and maps of the same; and the commissioner of the General Land Office shall thereupon number said sections so surveyed, and shall cause to be issued to said company, or its assignees, patents to the odd sections, the even sections being reserved to the State for the school fund; provided , that when fractions of land of a less size than twelve hundred and eighty (1280) acres, by reason of previous surveys are found, the same may be located by virtue of said railroad certificates, in equal quantities; and it shall be the duty of the Commissioner of the General Land Office to designate the same, as other railroad certificates, and to patent one-half thereof to the company, or its assignees, and one-half to the State; and the residue of said certificates may be in like manner located elsewhere, until the same is exhausted, the State being entitled to one-half of each survey, and the company to the other half; provided, that the grant of land herein made shall not be construed to give to said company a greater number of acres of land than the amount or number of acres computed, as herein provided, for the number of miles of road within the State of Texas. Sec. 4. That said company shall alienate the lands hereby granted and donated, except so far as may be necessary for the ordinary uses and operating said road as follows, viz: One-fourth thereof in eight years; one-fourth in twelve years; one-fourth thereof in sixteen years, and the remaining fourth in twenty years, from the date of the issuance of the certificates, in such manner that the whole of such lands shall pass out of the hands of said company within twenty years after the date of the certificates; provided, that said lands shall not be alienated to any other railroad corporation, except so far as may be necessary for the proper use and the conducting of the business of such corporation, nor to any person, firm or company, in trust for said railroad company, or to any company or firm of which any office or stockholder of said railroad company is a member; and the violation of the provision shall work a forfeiture of the rights conferred by this act; and on failure to comply with the provisions of this section, and the general laws of the State on this subject, or a violation of the provisions of this section or said general laws, the said company shall forfeit all right to lands secured by this act, not alienated as required by law. Sec. 5 That the public lands heretofore reserved from pre-emption, location and survey for the benefit of the Memphis, El Paso and Pacific Railroad Company, in what is known as the Memphis, El Paso and Pacific Railroad reservation, and as designated by the maps, plats and field notes now on file in the General Land Office, commencing on the eastern boundary line of the State, in Bowie county, and thence westwardly to the 23rd meridian of longitude west from Washington, are hereby continued to be reserved from pre-emption, location or survey, by the holder of any land certificate or other land claim, for the benefit of the said Texas and Pacifi Railway Company, and for the benefit of the school fund; and where the public lands therein have not already been sectionized, said company shall sectionize the same, and return the field notes and maps to the General Land office, as heretofore required, giving to the company the odd section, and to the school fund the even section; and said company is hereby authorized to apply an of the certificates to which it may be intitled uunder the provisions of this act , to the odd sections within said reservation; provided, that northin hrein contained sahll be so construed as to affect or impair the legal rights of third persosn; and further provided, that this reservations shall continue in force until the first day of January, 1876, and no longer. Sec. 6. That the said Memphis and el Paso reservation, from the twenty-third meridian of longitude west from Washington to the rio Grande river, as designated by the field notes, maps and reports of the different surveyors of the several land districts of the State, on filed on the General Land Office, is hereby continued to be set aside and reserved from pre-emption, location and survey for the benefit of said Texas and Pacific railway company and the school fund; and there is also hereby set aside for the same purpose, out of the public lands, such additional width of territory on each side of the said sixteen miles resercation as will make eighty miles in width from the twenty-third meridian of longitude west to the east boundary line of New Mexico, and to a point south of the south-east corner of said territory of New Mexico; that is to say, taking the centre line of said Memphis and El Paso reservation, and extending forty miles on eaither side thereof, and after reaching the said point south of, and opposite to the southeast corner of New Mexico, the said reservation of the unappropriated public domain is hereby continued eighty miles in width, extending westward to the Rio Grande, and bounded on the North by New Mexico, the same to include the Memphis and El Paso reservation hereinbefore mentioned, which said reservations, as herein continued and set apart, shall continue to be so reserved and set apart for the purposes herein mentioned until the year 1880, and no longer; provided, that nothing in this section contained shall impair or affect the rights of any person or persons heretofore legally acquired within said reservations; and provided, that the State of Texas shall have the right to grant the right of way, not to exceed two hundred feet in width, to any railroad company through or across said reservation, so long as the fee remains in the State, and to cross and connect with the road herein to be constructed. Sec. 7. That the Commision of the General Land Office shall designate, upon the maps of his office, the reservations herein continued and created from the twenty-third meridian of longitude west from Washington to the Rio Grande river. Sec. 8. That the certificates of land to which said Texas and Pacific railway Company may be entitled under the provisions of this act, shall be located within the reservations hereinabove continued and located, except one thousand certificates of six hundred and forty (640) acres each, to be issued to said company by the commissioner of the General Land Office upon such portion of completed road as it may desgnate, and which certificates may be located upon any of the public domain of the State subject to location not included within said reservations. And provided further, that in case there is not a sufficient quantity of unappropriated public lands within said reservations to satisfy the remainder of the certificates to which said company may be entitled with the corresponding sections belonging to the school fund, then, and in that event, said company shall have the right to locate the balance of said certificates, with the correspsonding sections for the common school fund, upon any of the unappropriated public domain of the State subject to location; provided, that the State of Texas shall not be helf responsible for any deficit of public lands upon which to locate said certificates. And no land certificates issued under the provisions of this act, which may not be loccated by reason of the exhaustion of the public domain, shall ever constitutee any claim against the State. Sec. 9. That the above grants, donations, and reservations are made to the said Texas and Pacific Railway Company, a corporation created by an act of Congress of the United States, approved March 3rd, 1871, as the assigness of and successor to the rights, privilehes and franchises of the Sotuhern Trans-continental and Southern Pacific railroad companies, corporations created by the laws of Texas, with the intent and distinct understanding that the same shall be accepted by said Texas and Paicifc Railway Company, in full satisfaction of any claims for money, bonds, or lands, to which said company might be entitled under the act entitled "An Act to encourage the speedy construction of a railway throught the State of Texas to the Pacific Ocean," passed May 24th, 1871, and "An Act amendatory of and supllementary thereto," Passed November 25th, 1871, or by virtue of the consolidation of said Texas and Pacific Railway Company with the southern trans-Continental Railway Company and the Southern Pacific Railroad company, or by virtue of the charters of either of said railway companies, or by virtue of any railroad franchise granted by the State of Texas, purchased or acquired by either of said companies or by the Texas and pacirfic Railway company, or by virtue of any general or special law of this Sate, and in full satisfac6tion of all claims or demands for bonds, lands or money of the the said Southern Pacific and south Trans-Continentla Railroad Companies againast the State of Texas; and said Texas and Pacific Railway Company shall be subject to such general laws as may be enacted by the Legislature, applicable to other railroads constructed within this State. And that all of the property of the said corporations, or either of them, now or hereafter situated in this State, shall be hereafter subject to taxation by the laws of this State. Sec. 10. That all railroads in this State, constructed, or that may be hereafter constructed, to intersect saud Texas Pacific Railroad, shall have a right to connect with... Continued at Gammel's Laws of Texas Go to top
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| 2. State Plane Coordinates |
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There have been several posts on State Plane (SPC) coordinates recently. Thought I would post a few thoughts about SPC coordinates for those not too familiar with them. SPC coordinates are a type of map coordinate developed by the USC&GS a predecessor to NGS in the 1930's. They were developed by USC&GS at the request of state DOT's to allow them to tie to and use NAD 27 coordinates produced by USC&GS when computing map coordinates for the DOT surveys. The objectives in developing the SPC coordinates were: * In a time of hand computations to minimize the computational effort * To limit the error in distances and angles introduced by using the map coordinates * To provide a uniform method of map coordinate to be used in an area These objectives were met by selecting SPC zones that were limited in size, covering no more than one state with given SPC definition and using more than one zone in large states, chosing either Lambert or Mercator map coordinates depending upon whether the state ran NS OR EW. One can understand SPC coordinates as the coordinates obtained by projecting surface points onto a three dimensional figure --- a cone (Lambert) or a cylinder (Mercator) --- that is then cut and layed flat to give a plane (ie flat) surface. The coordinates are then two dimensional Cartesian (x,y) coordinates. Think of the projection of the surface point as being a two step operation. First, the surface point is projected onto the reference ellipsoid of the datum being used in such a way that the projected point on the ellipsoid has the same latitude and longitude as the surface point. Then the point on the ellipsoid is reprojected onto the reference figure being used (cone or cylinder) using a complicated formula. The 3D reference figure has a specified geometric relationship to the reference ellipsoid and to the coordinate system of the datum. On the reference figure is a specified two axis coordinate system. When the 3D reference figure is cut and folded out flat the axes are 2D Cartesian coordinate axes and the location of points projected on the flattened reference figures can be specified by giving their 2D Cartesian coordinates, ie their SPC coordinates. The NAD 27 computations of latitude and longitude were obtained by USC&GS by first reducing all observations of distances, directions, and azimuths to the NAD 27 ellipsoid and then computing on the ellipsoid to obtain the latitudes and longitudes of the projections of the surface points on the ellipsoid these being computed so as to be the same as those of the surface points. Notice that to reduce the conventional surface observations to the ellipsoid USC&GS had to estimate the ellipsoid heights at the observation points. The Geoid heights were not known in those days, so for NAD 27 the coordinate system used resulted in the ellipsoid heights being, on the average, equal to the leveled (orthometric) heights across the US. Therefore, the leveled heights could be used in reducing surface observations to the ellipsoid when computing NAD 27 latitudes and longitudes by USC&GS and reducing observations to sea level by surveyors to compute their SPC coordinates. Of course, leveled heights were also be used with elevation factors to convert SPC distances back to surface distances. Notice that only latitude and longitude are needed to compute SPC coordinates, and the latitudes and longitudes of a surface point and its projection on the ellipsoid are the same. Since GPS gives the latitudes and longitudes of surface points directly, these can be used directly to compute SPC coordinates. The ellipsoid height obtained by GPS does not come into play in computing SPC coordinates. There is no reduction to the ellipsoid required to get GPS latitude and longitude. However, in going back from SPC to the surface ellipsoid heights are needed. For NAD 83 the ellipsoid and the GEOID do not agree so that in going from NAD 83 SPC distances to surface distances one cannot use leveled heights, but must use ellipsoid heights. Go to top
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| 3. NAD 83 Coordinate System |
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It was good to see useful discuss on coordinates from last night and this morning. Thought I would through in my two cents worth. First, I consider a coordinate system to consist of a set of 3D Cartesian coordinate axes (x,y,z) and a scale. A datum is a coordinate system and an associated reference ellipsoid. A coordinate system is specified by giving the location of the origin of its coordinate axes and the orientation of the axes. A coordinate system is said to be Earth fixed if its axes origin moves through space with the Earth and the axes orientation changes with changes in the Earth's orientation in space. Acoordinate system is said to be Earth centered if the origin is at the center of mass of the Earth. This is where you get the term Earth fixed, Earth centered coordinate system. You can have coordinate systems that are not Earth fixed. For example, to describe the orbits of the planets you would use a sun centered, sun fixed coordinate system. What happens with a coordinate system is that you define what you want to achieve, then you develop mathematical models, take observations and compute coordinates. This is refered to as realizing a coordinate system by determining the coordinates of a group of reference stations. These reference stations' coordinates can be refered to as a reference frame. One can start out with a description of what you want the reference frame to be. Then you take the models and observations and compute your coordinates. The coordinate system to which these coordinates refer may not be quite the coordinate system you wanted because of some of the models were not quite right. So if you want to you can change models and try again. The NAD83 coordinate system was defined and realized in the mid 1980s before there was an ITRF or GPS observations. The aim was to have an Earth fixed, Earth centered coordinate system. The coordinate system was to have the axes origin at the center of mass of the Earth. The scale was to be in agreement with laser tracking of satellites. The axes orientation was to agree with the CIO pole and zero longitude as derived from optical star observations. Almost all of the stations going into the NAD83 solution were conventional observations that provided only latitude and longitude and were not accurate in terms of what we call accurate today. There were a few hundred satellite Doppler stations that gave 3D coordinates accurate to about 1 meter and 10 or 20 VLBI stations that gave coordinates that were accurate at the few centimeter level relative to the resulting NAD83 coordinate system that was realized. The coordinates of this few VLBI stations are what has defined the coordinate system of the NAD83 realization. These VLBI stations are all on the North American tectonic plate. So what did the realized coordinate system look like. Based on ITRF results since then we have found that the origin of the NAD83 coordinate system is actually offset from the center of mass by about 2 meters. The scale was off by a small amount (I forget the exact number) and NAD83 scale was adjusted soon after 1986 to agree with VLBI scale. The orientation of the axes were off by a few tens of arc seconds at any given time if compared with ITRF results. The axes of the NAD83 coordinate system were rotating in space with the North American plate with a high degree of accuracy. The agreement was so good that, to the dergee that the North American plate is moving relative to the NAD83 coordinate axes is no more than 1 or 2 mm/yr. Thus, it was decided to keep the NAD83 coordinate system as realized by the coordinates of the VLBI stations coming out of the original NAD83 solution. Thus NGS has developed transformations to transform results coming out of the ITRF solutions to this NAD83 coordinate system. Re: Thanks for One Clarification. Posted By Lawrence Paul Lopresti I was confused by your statement yesterday that NAD83 movement was less than 1mm/yr. It is clear now that you meant the disgreement with the North American plate and NAD83 is less than 1mm/yr. NAD83 and the North American plate are moving about 11mm/yr relative to ITRF which also means relative to Lat & Long. If I were to use the position of a iron pin in the ground as per NAD83(96) SPC PA S, that position is now 0.3' from where it was. I would not be in conformance with PA requirements of an uncertainty of 0.1' in position. That is unless SPC PA S is calculated today using the origin Lat & Long where it was in 96 and not where that exact Lat & Long is today. Paul in PA Re: NAD83 Coordinate System Posted By Mister Geodesist Motion is relative to what coordinate system you use. The North American Plate in the US is moving about 2cm/yr relative to the ITRF00 coordinate axes and about 1 to 2 mm/yr relative to the NAD83 coordinate axes. That is NAD83 Lat/Long interior to the North American Plate changes 1 to 2 mm/yr while ITRF00 Lat/Long changes by 2 to 3 cm/yr. You can create a coordinate system that is just as valid, relative to which the Lat/Long of points on the North American Plate were moving 10 cm/yr. NGS chose to keep the NAD83 coordinate system because the motions relative to it in most of the US can be ignored for a number of years and will be modelable to fractions of a mm/yr in a few years. Re: HOLD ON ONE MINUTE! Posted By Lawrence Paul Lopresti Are you saying there is an NAD83 Lat & Long as well as an ITRF Lat & Long? That I cannot believe and I feel it is unacceptable. If the NAD83 Lat & Long are tied to the North American plate, then they are also skewing relative to true Lat & Long. The PLSS was based on EW and NS lines. They were laid on the ground more than 100 years ago. Do you have a skew correction for the PLSS surveyors to walk in their predecessors footsteps. I disagree with your statement "can be ignored for a number of years". Land lasts longer than a number of years. You have just said that you are promoting a system that in a number of years will be defective. Shame on you and the NGS. I say "Coordinates as defined by you are not suitable monuments for boundary line survey use". Paul in PA Re: NAD83 Coordinate System Posted By Eugene Kooper Paul, Yes, there NAD83 lat/longs AND ITRF lat/longs. Just look at any OPUS report and you'll find the position of your control point expressed in both. Gene P.S. Or look at a USGS 7½ quad map. In the lower left corner, you see something like "North American Datum of 1983 (NAD 83)is shown by dashed corner ticks". For example the NAD 83 tick mark for 39° 7' 30" N, 106° 15' is about 50 meters east of the same lat/long in the NAD 27 datum. I Disagree Mr. G Posted By Lawrence Paul Lopresti Your letter to the editor (American Surveyor) states that NAD83 has not changed. Yet NAD83 SPCs are based on Lat and Long origins. NAD83 is moving relative to Lat and Long. Sounds like further explanation is required. I find it Strange that something can move and remain the same at the same time. Paul in PA Re: I Disagree Mr. G Posted By Steve Kersey The shape of a datum can remain the same even when the origin is moved or when the datum is translated or rotated. Re: I Disagree Mr. G Posted By Dave Doyle The fact that a coordinate changes does not mean the datum has changed. Coordinates within NAD 83 have changed because of their improved "precision" relative to the definition of the datum. A horizontal datum is defined by 8 parameters, 3 each define the location of the origin and orientation and 2 define the size and shape of the reference ellipsoid. None of these have changed for NAD 83, nor will they change with the national readjustment. Re: I Disagree Mr. G, Your replat request was denied... Posted By J. Anthony Cavell Dave and Steve are, of course, correct. NAD83, unlike classical datums, is not defined by the measured points on the ground, but rather they by it. That said, Paul's statement, "I find it Strange that something can move and remain the same at the same time," (despite tongue-in-cheek references) is exactly what the young intern will be thinking as he tells you (with the full weight of city hall behind him) "your survey is wrong. The coordinates don't match the record." Regards, Tony Cavell PLS- La. Go to top
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| 4. How GPS Carrier Phase Positioning Works |
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| 5. Where coordinates come from |
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| 6. The WGS84 Myth is still present |
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WGS 84 Discussion For questions or to submit additional material, please email Andy Nold
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