Hilger Watts Theodolite Manual

To understand the manual, you must first understand the maker. Hilger & Watts was formed in 1948 from the merger of two London-based firms: Adam Hilger, Ltd. (specializing in optical spectroscopy) and E. R. Watts & Son (manufacturers of surveying and geodetic instruments). The union produced some of the most robust and optically superior theodolites ever made.

Unlike the ubiquitous Wild T-series or the Zeiss Th movement, Hilger Watts instruments were designed with a distinctly British philosophy: over-engineered, heavy, and capable of surviving decades of field abuse. Their optical systems used the "Watson’s prismatic circle reading" method, which allowed for precise readings to 10 seconds of arc or better without the need for a microscope.

Production peaked in the 1950s and 1960s. By the 1970s, the rise of electronic theodolites and total stations (like the Hewlett-Packard 3820) made these optical wonders obsolete. However, because they were built like tanks, thousands still exist in storage sheds, university geology departments, and estate sales.

  • Ensure instrument is directly over the ground mark; use optical plummet to fine-center.
  • Re-level after centering as necessary; any movement affects centering and accuracy.

    • Key point: Accurate leveling and centering are foundational—small errors magnify in angular readings and downstream coordinates. hilger watts theodolite manual

    While waiting for your Hilger Watts theodolite manual to arrive, here is the universal workflow for their 1950s–60s models:

  • 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.

    This is the most unique part of Hilger & Watts instruments. The manual describes a coincidence method: To understand the manual, you must first understand

    Example: Circle shows 45°; micrometer reads 12' 30" → 45° 12' 30".

    These were smaller, less precise instruments (often 20-60 arc-second), designed for construction and mining.

    Often found in olive-drab carrying cases. The manual for the M2 includes sections on: Ensure instrument is directly over the ground mark;

    List of user-adjustable errors with step-by-step:

    Note: Factory-only adjustments (e.g., circle graduation errors) are clearly marked.