"Jolly balance" meaning in English

{
  "etymology_text": "Invented by the German physicist Philipp von Jolly in 1864.",
  "forms": [
    {
      "form": "Jolly balances",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Jolly balance (plural Jolly balances)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
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          "source": "w"
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          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
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      ],
      "glosses": [
        "An instrument for determining specific gravity by comparing how much an object stretches a spring when held in a pan hanging in the air to how much that same object stretches a spring when held in a pan underwater."
      ],
      "id": "en-Jolly_balance-en-noun-i4dUz7GJ",
      "links": [
        [
          "instrument",
          "instrument"
        ],
        [
          "specific gravity",
          "specific gravity"
        ]
      ]
    }
  ],
  "word": "Jolly balance"
}

{
  "etymology_text": "Invented by the German physicist Philipp von Jolly in 1864.",
  "forms": [
    {
      "form": "Jolly balances",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Jolly balance (plural Jolly balances)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys"
      ],
      "glosses": [
        "An instrument for determining specific gravity by comparing how much an object stretches a spring when held in a pan hanging in the air to how much that same object stretches a spring when held in a pan underwater."
      ],
      "links": [
        [
          "instrument",
          "instrument"
        ],
        [
          "specific gravity",
          "specific gravity"
        ]
      ]
    }
  ],
  "word": "Jolly balance"
}