The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3M Company COM 88579y101 19,296 115,803 SH   SOLE   0 0 115,803
Abbott Labs COM 002824100 594 14,209 SH   SOLE   0 0 14,209
Abbvie Inc. Com COM 00287y109 814 14,246 SH   SOLE   0 0 14,246
Alphabet Inc Cap Stk Cl A COM 02079k305 245 321 SH   SOLE   0 0 321
Amazon Com Inc Com COM 023135106 322 542 SH   SOLE   0 0 542
Apple Computer COM 037833100 6,042 55,437 SH   SOLE   0 0 55,437
Auto Data Processing COM 053015103 19,489 217,250 SH   SOLE   0 0 217,250
Becton Dickinson COM 075887109 311 2,051 SH   SOLE   0 0 2,051
Bellicum Pharmaceutica Com COM 079481107 791 84,612 SH   SOLE   0 0 84,612
Berkshire Hathaway Cl B COM 084670702 280 1,975 SH   SOLE   0 0 1,975
Black Stone Minerals L Com Uni COM 09225m101 995 70,998 SH   SOLE   0 0 70,998
CVS Health COM 126650100 14,729 141,996 SH   SOLE   0 0 141,996
Chevron Corp COM 166764100 2,118 22,198 SH   SOLE   0 0 22,198
Coca-Cola Co COM 191216100 18,340 395,335 SH   SOLE   0 0 395,335
ConocoPhillips COM 20825C104 233 5,786 SH   SOLE   0 0 5,786
Donaldson Inc COM 257651109 17,315 542,606 SH   SOLE   0 0 542,606
Dorchester Minerals LP Com Uni COM 25820R105 604 53,023 SH   SOLE   0 0 53,023
Dover Corp COM 260003108 14,054 218,469 SH   SOLE   0 0 218,469
Ecolab Inc COM 278865100 19,414 174,087 SH   SOLE   0 0 174,087
Emerson Electric Co COM 291011104 15,011 276,030 SH   SOLE   0 0 276,030
Exxon Mobil Corp Com COM 30231g102 3,063 36,639 SH   SOLE   0 0 36,639
FedEx Corp COM 31428x106 18,438 113,310 SH   SOLE   0 0 113,310
Halcon Res Corp Com New COM 40537q209 50 52,445 SH   SOLE   0 0 52,445
Home Depot Inc COM 437076102 202 1,517 SH   SOLE   0 0 1,517
Honeywell International COM 438516106 14,085 125,706 SH   SOLE   0 0 125,706
Illinois Tool Works COM 452308109 21,074 205,719 SH   SOLE   0 0 205,719
Intel Corp COM 458140100 18,111 559,831 SH   SOLE   0 0 559,831
International Business Machine COM 459200101 524 3,459 SH   SOLE   0 0 3,459
Johnson & Johnson COM 478160104 19,316 178,520 SH   SOLE   0 0 178,520
Luminex Corp Com COM 55027E102 760 39,175 SH   SOLE   0 0 39,175
McDermott Intl Inc COM 580037109 44 10,850 SH   SOLE   0 0 10,850
Medtronic PLC COM 585055106 697 9,297 SH   SOLE   0 0 9,297
Microsoft Corp COM 594918104 22,367 404,981 SH   SOLE   0 0 404,981
National Instr Corp COM 636518102 14,742 489,601 SH   SOLE   0 0 489,601
Nokia COM 654902204 89 15,100 SH   SOLE   0 0 15,100
Nordson Corp COM 655663102 21,351 280,786 SH   SOLE   0 0 280,786
Novartis AG COM 66987V109 13,678 188,823 SH   SOLE   0 0 188,823
Paccar COM 693718108 14,190 259,466 SH   SOLE   0 0 259,466
PepsiCo Inc COM 713448108 17,893 174,598 SH   SOLE   0 0 174,598
Phillips 66 COM COM 718546104 246 2,843 SH   SOLE   0 0 2,843
Procter & Gamble COM 742718109 17,750 215,645 SH   SOLE   0 0 215,645
Sabine Royalty Trust UBI COM 785688102 414 14,000 SH   SOLE   0 0 14,000
San Juan Basin Royalty Trust COM 798241105 3,334 647,452 SH   SOLE   0 0 647,452
Schlumberger Ltd COM 806857108 13,870 188,074 SH   SOLE   0 0 188,074
Stericycle Inc Com COM 858912108 220 1,740 SH   SOLE   0 0 1,740
Telefonica de Espana COM 879382208 544 48,868 SH   SOLE   0 0 48,868
United Parcel Svc Cl B COM 911312106 16,434 155,816 SH   SOLE   0 0 155,816
W.W. Grainger COM 384802104 20,285 86,898 SH   SOLE   0 0 86,898
Waste Management Inc Del COM 94106L109 215 3,645 SH   SOLE   0 0 3,645