3. Swiss citizens in foreign countries, if they are subject to a personal service or to an exemption tax for the same in place of domicile. 4. The railway and steamboat employés during the time when they are liable to the military service organized for the working of the railways and steamboats in time of war. 5. Policemen and the federal frontier guards. This military tax consists in a personal tax of six francs, and of an additional tax on property and income; the amount exacted from any one tax-payer not to exceed 3000 francs per annum. The additional tax is one franc and a half for each one thousand francs of net fortune, and one franc and a half for each one hundred francs of net income. Net fortunes less than 1000 francs are exempt, and from the net income are to be deducted 600 francs. Net fortune is the personal and real property after deducting debts of record, chattels necessary for household, tools of trade, and agricultural implements. Real estate and improvements are assessed for this tax at three-fourths of their market value. In computing the property of a person for this tax, half of the fortune of the parents, or if not living, then of the grand-parents, is included, proportionately to the number of children or grandchildren, unless the father of the tax-payer shall himself perform military service or pay the exemption tax. Net income embraces: 1. The earnings of an art, profession, trade, business, occupation, or employment. The expenses incurred to obtain these earnings are deducted, also necessary household expenses, and five per cent. of the capital invested in the business. 2. The product of annuities, pensions, and other similar revenues.