The Beardslee telegraph machine, developed in the mid-19th century, had several technical deficiencies that limited its effectiveness and adoption:

1. Limited Range: The Beardslee telegraph was designed to function without batteries, relying on mechanical means for operation. This design inherently limited its range, making it unsuitable for long-distance communication compared to battery-powered telegraphs.

2. Complexity of Operation: The machine required manual operation, which was more complex and labor-intensive than the more automated electric telegraphs. This complexity made it less practical for widespread use, especially in military applications where speed and efficiency were crucial.

3. Signal Clarity: Due to its mechanical nature, the Beardslee telegraph often produced less clear signals compared to electric telegraphs. This could lead to miscommunication, especially over longer distances or in adverse conditions.

4. Speed Limitations: The mechanical operation of the Beardslee telegraph was slower than electric telegraphs, which could transmit messages more rapidly. This slower speed was a significant drawback in scenarios where quick communication was essential.

5. Maintenance Issues: The mechanical components of the Beardslee telegraph required regular maintenance and were prone to wear and tear, which could lead to operational failures. This made it less reliable in field conditions where maintenance resources were limited.

These deficiencies contributed to the Beardslee telegraph being overshadowed by more advanced and efficient telegraph systems that utilized electrical signals and batteries, ultimately leading to its decline in use.