• Annual: Full calibration by trained technician or manufacturer service center, including checking circle graduations, spindle bearings, and optical collimation.
  • Long-term storage: Desiccate case, remove batteries (if applicable), and store in stable temperature environment.

    • Avoid DIY internal adjustments unless trained; misadjustment risks more error than leaving a small known offset.

    To appreciate the manual, you must first appreciate the machine. Adam Hilger founded his company in London in 1874, specializing in scientific spectroscopes and astronomical instruments. In 1948, the company merged with E. R. Watts & Son, a firm famous for its surveying instruments and optical dividing engines. The resulting entity, Hilger & Watts Ltd., became a powerhouse in precision optics.

    Their theodolites were distinct for several reasons:

    The most famous models include the Microptic Theodolite (Models T0, T1, T2, T3) and the Watson "M" Series. Each model requires a specific Hilger Watts theodolite manual due to differences in their clamping systems, bubble levels, and micrometer optics.

    Let’s assume you have obtained a Hilger Watts theodolite manual for your Microptic T2. Here is a typical calibration workflow drawn directly from the manual’s text:

  • Record metadata: temperature, pressure, humidity (for long lines or refraction-sensitive work), instrument temperature, and operator.

    • Practical tip: Use two-person teams (one at instrument, one at target) to improve speed and reduce parallax errors.

    Often found in olive-drab carrying cases. The manual for the M2 includes sections on:

    Companies that sell refurbished vintage surveying equipment (e.g., Rigby’s Surveying Instruments in the UK, Timbeter in Europe) sometimes have a library of original manuals. They may sell a photocopy for a small fee ($15–$30).